So I haven't yet tried this card out. I'm planning on running it in a "Skids" O'Toole deck soon, and I definitely want to test it in Preston Fairmont since you can spend one FI resource on this card to turn into 10 resources later that skip Preston's ability by going directly to the resource pool (though I still debate the marginal benefit given that he gains so many resources a turn anyway). However, I am going to vouch for its usefulness given its rather polarized reception, and encourage you to test it out yourselves.
First off, this card is not Emergency Cache. The cards are both economy cards, sure, but they intend to do very different things. E-Cache is all about resources now to help you buy something now. It's a tripled resource gain action, which is very efficient. Investments is about resources later, and not all decks care about having resources later. Do you have expensive allies like Agency Backup or resource hungry ones like Lola Santiago? Do you have resource sinks like Streetwise, Higher Education, or Skids' action ability? These are things that Investments helps with.
Second off, I don't agree that E-Cache is a less useless late game draw than Investments. You either draw this early on and have significant late game sustain, OR you commit it late game for an on an investigate test, which is something that is, for the most part, relevant all scenario long. How often do you really need those extra three resources late game anyway? The majority of economy cards (Lone Wolf, Drawing Thin, Dr. Milan Christopher, etc) are best drawn turn 1, but you will still run them and will still play them mid game (I'd argue that's true for Milan even if he didn't have the +1 boost).
Lastly let's talk about the opportunity cost of this card- again, in regards to its most comparable replacement, Emergency Cache. E-Cache is 1 action for 3 resources. Investments costs an action and 1 resource, and doesn't pay off net the way E-Cache does until you hit 5 resources (5 - 1, and another -1 for the extra action), and that takes 5 turns. Yes, it's slow. But again, it's not about raw power or efficiency, it's about flexibility. If you're reluctant to take the resources off this thing just because it feels bad to make a play that is objectively less efficient than just having played E-Cache, you're not using the card right and giving in to sunk cost fallacy. Let's think about this card at every resource quantity, and what it actually provides you given that you're willing to trigger it at any point, from a piloting standpoint:
1 Resource - You will never do this because it's objectively worse than a 'gain a resource' action.
2 Resources - You probably wont do this unless you really need two resources right now. Most people are willing to wait an extra turn if they can't get all their resources now.
3 Resources - This is now an interesting card. From this point forward you have at least an E-Cache on demand for the rest of the game, similar to having an E-Cache in your hand, except it gets stronger if you do choose to wait. Yes, you already spent 1 action to get this here and you could have drawn E-Cache instead, but ignore the sunk cost. If you need those 3 resources, crack it. Don't be afraid. You would just as well have played E-Cache if you needed to, don't be reluctant to crack this.
4 Resources - This is where I personally believe the card gets good. Again, ignore the sunk cost, this card now lets you afford just about any card in the game for 1 action (given that you got a resource last turn as well). 4 turns into the future isn't even necessarily bad late game, but if it isn't worth the net 3 resources, go and throw this onto an investigate test.
5 Resources - Net 4 is now more potential than E-Cache. You still spent two actions to get them, fair enough. But you spent that extra action for the flexibility of cracking it earlier or later than this if you need to.
6 Resources - I think this is where a lot of players feel the card becomes "worth it", in that its raw power or efficiency beats playing E-Cache. Mathematically this is probably true, but again, don't wait 'till 6 to crack this just because it feels more efficient. If you need it at 5, or 4, or 3, go for it. That extra action you paid allows you flexibility, that's what you're paying for.
7+ Resources - The question at these quantities becomes what you can even spend these on. Obviously if you have resource sinks you don't have to worry about that- again, something I think you need in your deck to run this card well. The question of whether sinking 7 now vs 10 late (or something in between) depends heavily on the scenario, the deck, and the amount of time you think you have left. How much is that one extra resource later worth? How much is impacting the board state now worth? Do you need to pop out a Lightning Gun and take care of a monster now, or do you need those resources to invest into Lola Santiago later?
So in summary, I think people are understandably reluctant to run Investments because, for a lot of decks, it will just be a worse choice than Emergency Cache. But as I said at the the top, the cards function differently. Anyone who can take advantage of waiting for these resources to accrue will run this over E-Cache ten times out of ten. Investments is a terrifically powerful card, but it demands to be used in a very particular kind of deck. I am personally excited to try it out with a couple of Rogue decks I'm brewing, but if you need some current proof of its usefulness, jamjams32 swears by it for his Leo Anderson deck: arkhamdb.com
If nothing else, Rogues have never been afraid of trying 'iffy' cards just to see if they work (this is the faction with Double or Nothing after all). I say if you're on the fence to give it a go and see what happens.