a) $25k is not a lot of money for very well-known programmers. There are fairly straightforward methods to get that much in a month (a salaried job), a week (contracting+), or a day (training event, $500 a head).
+ Stipulate that in addition to Rails he has at least one talent which makes money and this is not unreasonable at all.
b) There was no time at which OSS was not predominantly the work product of the global rich employed at corporations. This is observably true for Rails, since the list of contributors since DHH extracted it is both public and short. The Rails core team works on Rails like it is their job because...
c) ... Rails was designed to, and succeeds at, making companies great piles of money by increasing the efficiency at which they can churn out CRUD apps. Please note that is in no way a criticism. Apps running on Rails go from BCC (five figures a year) to Basecamp (eight figures a year and will probably hit nine eventually unless they already did).
d) OSS developers making money by it - I.e. The traditional accepted way to write it - does not make you personally worse off, because it increases software available to you. You may perceive that people will listen to you less because monied interests will drown out your voice. This is irrational: since the $100 you think is a lot of money only buys maybe 30 minutes of programmer time anyhow, the opinions that mattered in OSS were already those of companies which coul actually pay salaries, and someone freer with their last $100 than you are will only have epsilon more impact on "the community" than you when compared to IBM (a consulting company which staffed most Linux development) or Google (an advertising company which directly or indirectly pays the salaries of the majority of programmers working on either of the two big OSS browsers.) apache's Kickstarter was IBM realizing that they'd happily pay a billion dollars to have IIS not become the dominant server platform so they proceeded to do so.