Aris,
“Possession of marijuana is a felony offense, right?“
To my knowledge, “recreational” amounts are legal in most states. It is like firearms laws; check state laws carefully before going on interstate vacations.
“I mean you say ‘felons’ and some people may be thinking that ‘felons’ means murderers and rapists -- rather than guys who had weed on them.“
That is the general idea. Financial crimes might also be included.
“12% of US adults smoke marijuana. So that's at least 12% of US adults that should be disenfranchised, according to you.“
No, look into current U.S. laws, by state.
“(of course, in reality you're only really in danger of being charged with the crime of possessing marijuana if you're non-white)“
Under federal law, if you start hauling bales, or cultivating in distribution quantities, expect felony charges regardless of ethnicity.