Probably a few things, the same factors which lead someone to troon out are probably also temporarily alleviated by weed (as a numbing cudgel masquerading as a warm blanket), trannies tend to accumulate in areas where weed is legal and where weed is legal it can absolutely be cheaper than booze if you buy in bulk, and top it off with there being enough co-morbid unaddressed mental issues that an addictive personality ends up in there somewhere.