A quote from Daniel James of Three Rings

DRM takes a big poo on your best customers—the ones who’ve given you money—whilst doing nothing practical to prevent others from ‘stealing’ your precious content juices. Worse, it makes these renegades feel nice and righteous about sticking it to ‘the man’. Stop trying to persuade people to love you more by hitting them a rusty pipe. Put down the pipe, and give up on DRM