A lot of groups have a buy me a coffee if a large number of their members are at the free or free-ish level like mine, a $1 a year, again it's to keep bots out.
People tell me all the time, I give away too much for $1 a year, well now there will be an option to buy me a coffee.
But if you know me, I have a generosity fault, so each month will have an easter egg in the coffee. (Yum, who does not love egg flavored coffee!)
Something that is no where else to be had! It will go poof after a month.