After my young childhood Big Box Store POS's, my first "real" bikes started when I was 14 in the early 90's and had my first 5 within a couple years, bought myself with my paper route and detassling corn:

1) KHS Classic steel road Suntour-Accushift-something
2) Trek 850 steel mtn rigid steel fork hardtail Suntour-something
3) Cannondale SR600 aluminum criterium 105
4) Nishiki steel time trial (700c rear, 24" front) 105
5) Trek 7000 aluminum mtn rigid steel fork hardtail LX/XTR

... Then came 1 more by age 16:

6) '93 Cannondale Delta V full suspension mtn Suntour XC Comp

... And 1 more by age 20:

7) '97 Cannondale Super V full suspension mtn Suntour XC Comp