Question: There's a certain kind of people who like to hoard whatever limited resources they get "just in case"; they usually end up never using them, always waiting for bigger emergency. On the other hand, there are game mechanics based on spending some limited resourse: like bennies in Savage Worlds, fortune points in Warhammer, etc. You're supposed to spend them liberally, getting some in-game benefits. 

The "hoarders" never spend these, robbing themselves of part of enjoyment. Simply explaining that "those point are meant to be spent" doesn't always work: players seem to understand that rationally, but some force of habit still prevents them from actually using their resources. I think this happens more often in videogames (I myself am guilty of hoarding all goodies till the end boss, and then never needing them), but I've seen this kind of behaviour in tabletop games too. 

Of course, some players do this because they just like hoarding, or because they like the additional challenge, but some do notice that they're "doing it wrong."

Is there maybe some sort of trick to encourage resource spending? 

**Clarification**
I'm mostly interested in "mechanical" resources like fate points and bennies. If you hoard something material, like potions, or money, at least you (probably) have more money as a result. When you hoard bennies, you essentially forfeit your chance to *do* something that matters. This is probably not what players want.

Answer: 
*Is there maybe some sort of trick to encourage resource spending?*

Yeah - have a look at real life first. What prevents you from hoarding anything you can afford to acquire? Two things: 

1. storage space/costs.
2. some goods have a "best before" date (or require even more storage resources)

Note that 2 applies even to non-physical things. I.e. if you learned French in high school "just in case", you will probably lose most of it unless you practice it, watch French movies, go to refresh courses and so on.

So, if it's a in-world resource (like potions), see that points 1&2 apply. If the PC is hoarding stuff and carrying it along all the time, apply saving throws to see if any of that is damaged when he is hit, too (AD&D had something this since the oldest editions for example).

If it is a "meta-gaming" resource like bennies, experience points, fate points, hero points etc. ... enforce some "stale/storage" scheme. 

Like "you can't ever hold more than your level in fate points - if you are 7th Level and get one extra fate point you lose it automatically".
**Give out bennies like candy.** No, really. As long as your PCs are comfortable with the "refresh rate" of their valuable resources, they stop being all that valuable.

Don't forget to award the antagonists with something also - more mooks, more bennies, whatever. Your players should not feel the game suddenly becoming easier, but the opposite (you're aiming for "Man, we're lucky we spent all those bennies, otherwise we'd be toast now!").

Once they grow out of hoarding, you can dial down a bit and reward only their best moments with ~~candy~~ bennies.