Seems to me, the volunteers are more hard put to it, since they actually have to lose money to do this, essentially taking a pay cut from their normal careers as opposed to getting money to do it. I'm not getting your argument, or youre presenting it poorly.
The difference is that the volunteers are doing this for passion alone, the professionals are doing it for a paycheck... some may have passion, others may not, just like every single other job out there.
As for work hours... this is 2018, since the advent of the internet and VPN, there's almost no job out there that doesn't work M-F 8-6, plus overnights and weekends.
Calling it a hobby or calling it a passion matter.
"Theres a difference."
and THAT is where your condescension comes clearly into view.