Nobody should be asked to make bets on their medical needs.

Your entire argument sounds very much like how certain religions are against insurance because they view it as gambling.

It's led to the rise of an even riskier practice of shared health benefit pools, which market themselves as not being insurance even though they're pretty much the same thing as "mutual insurance," except that when you need them most, suddenly they're not insurance at all.

It also sounds very young. When you get over a certain age, you WILL use up that FSA. Every. Single. Year.

And if you're young enough not to, there are plenty of over-the-counter everyday goods that qualify for FSA, like Tylenol.