As a last point, I would like to mention that I was able to work on this almost full-time while being a part-time research assistant at the Legal Priorities Project. Maybe this is not an option for everyone, although there are a lot of grant opportunities right now, see here. I am uncertain how well my approach is suited for someone who can only use their spare time for it – my best guess is that it would still work out, but simply take longer.
I strongly encourage people to consider applying for one or more of these things. Given how quick applying often is and how impactful funded projects often are, applying is often worthwhile in expectation even if your odds of getting funding aren’t very high. (I think the same basic logic applies to job applications.)
See also List of EA funding opportunities, including this statement: