Starting to mine with one gpu is like having one tattoo..
You're almost certainly bound to add few more 😁
..and yes, speaking from experience, on both ends.
I had the same experience. i started from one, now have 6.
Used a gaming rig to mine sometimes while sleeping. Saw my wallet on that coin recently and wished I went all out back then. So yeah start out mining small to get a feel for how it works before building a new PC purely for mining when not gaming.