Currently, I have five bikes.
1 - hard tail mountain bike - hardly used. Intended to be used for road grade climbing training (because of its lower gear ratios). Probably could do without it.
1 - flat bar road bike w disc brakes - used occasionally. Intended for general purpose cycling but with some long downhill rides also (hence the disc brakes for improved/sustained braking).
1 - flat bar road bike - used occasionally. Used for general purpose cycling (mostly) on flat roads.
1 - flat bar road bike w triple crank - used occasionally. Intended use for some grade climbing (training) as well as general purpose cycling.
1 - flat bar hybrid bike w triple crank & disc brakes - hardly used. Bought after the mountain bike. Intended to be used for grade climbing training; has mountain bike low gear ratios. Probably could do without it.
As I'm not really fit, I bought the triple cranked bikes to help with cycling up hill roads. My fitness is still work in progress. When (if) my fitness improves, I'll probably sell the mountain and hybrid bikes as they will no longer be needed.
Considering that I have limited income at this time, I have bought more bikes than I really need.