We've been running a Functional Analysis reading group on the EleutherAI Discord (partially motivated by a desire to grok Infrabayes). According to hard earned advice it's useful to pair up when learning difficult things.
We're as of this posting on section 2.3 of "A Friendly Approach To Functional Analysis" (which TurnTrout reviewed and may be found on libgen). I should have posted here sooner, but better late then never. A motivated person can still catch up (we're going at ~2 sections/week, I'm spending ~5hrs/wk, if you spend more you can easily catch up).
TlDR get on EleutherAI's discord and join the Functional Analysis Thread!
PS: I'm likely to start other reading groups in the future, comment if you're interested in one on abstract algebra, calculus on manifolds, logic, probability, since those are what I'm currently interested in.