3.1 was still nice compared to its main competitor, which was MacOS 7. Only the richest kids would be running things like Solaris, SCO, and other preemptive multitasking systems because memory demands were high and memory was very expensive.
Also, Windows 3 would run on 286 computers (as would OS/2), which made the barrier of entry very low. I started running it on a 286 with a Hercules adapter.