I started as the 'mid life crisis' thing, drums were too noisy and guitar looked too difficult, bass it was then.
I was actually one of those who was playing in a band after 3 months, mind you they had to play exactly the right songs, in the right order otherwise I was bu66ered!! there is a youtube vid somewhere of me playing at our 1st ever gig..petrified at the back of the stage, frozen in place lol..I think I played roots all night.
Fastest way to learn is get in with a band, seriously more fun and steeper learning curve than playing along at home or taking lessons, but so much more rewarding.