I never actually owned a TRS-80 but I used one at a computer club I joined when I was 14. I spent the first couple of weeks playing Haunted Mansion and then decided it was time to write my own programs. I read the BASIC manual in a single night and started working on my first project.
BASIC was an easy to learn computer language, but it wasn't well suited for games. I found that out pretty quickly after starting to work on my first computer game, a TGV (Train à Grande Vitesse or french bullet train) simulator, an idea suggested by a good friend. However, performance was sluggish, at best. That is why I discarted BASIC and for the next ten years or so, assembly (6502, 65C816 and 680x0) became my language of choice.