Guitar. Pedals, amps, cables, picks, more picks, straps, strings, mics, stands, clamps, etc all add up. Oh, and of course you're always enticed to upgrade, but you can't get rid of the one you've grown to love, so now you have n+1 guitars.
To be clear, you can do amazing things with a Fender Bullet, but it's a slippery slope for sure.