Soldato
At 16 I wanted the freedom to take myself to work so got a 50cc moped to allow me not to require a taxi or parents for a lift.
This thing was poor, great on the flat nice and nippy and did 40 no worries which was fine for the trip to work but any other distance where speed limits were more I was holding traffic up, plus it did a dizzy 18mph up hills!
So, 17th birthday saw me get a geared 125, Honda CBR. This is when it became a bit "fun", 6 months later I did my test and I was driving a CBR 600 at 17, 33bhp of course but still good for proper riding and getting it leaned over.
Its the sheer pain of missing the feeling thats leading me to selling my perfectly adequate car, getting something with a smaller engine and getting myself back out on 2 wheels again
So, in answer to the OP, it was a gradual thing that soon became a part of who I am!
Sounds all a bit like me... My yearly motoring cost always took into consideration the cost of owning a bike too. I always had to have a nice car, but always needed a decent bike too. Which probably led me to go with a car a couple of yrs older and with what I would have spent, get a bike !!