For developer tools you use every day, I think $100 is a relatively small amount and in line with what a lot of text editors and IDEs charge for (and less than many of them).
I don't see it as chipping in $100 for Lighttable itself (which I do want), I see it as showing there is a very real demand for new thinking in IDE-land.
It's only $100 so there's no need to forsake anything. I bought a personal license for IntelliJ IDEA, for example, and I upgrade to every new version. I believe in buying software that makes me more productive.
I find it kind of strange that people in the software business have such a hard time paying for software. I hope this doesn't rub off on the general population.
In this case, personally, I am.