If someone earns a substantial amount of XCoin that he does not intend to spend in a couple of months, he should use it to buy some more profitable investment. That is how a currency is supposed to be used.
In an ideal world, this might be the case.
In the real world, when investments are more profitable than holding currency, in some significant cases this is because the economy is in a bubble state. What would happen if investors didn't have a way to step out of the game and say: "whoa, this is getting a bit rich for my blood!"? Selling assets for currency is one way of doing this, and is an important check on the boom part of the boom-bust cycle. This is what the idea of non-political money stems from in the first place - if the valuation of a currency can be centrally controlled, then market cycles can be manipulated beyond what the markets would otherwise support.