For me, it was all about the money.
I saved money on bike parts by getting pro deals.
They paid my race entries.
I made a boat load of money racing the last season I raced "seriously" on the road. Like, $4k.
I realized that I wasn't strong enough to roll off the front of a 100 man P/1/2 race pretty early on. I did, however, realize that I was adept at working on the front late in the race, getting bottles, and leading people out for primes and the final lap. So, I did that, and did it well.