Ironically my flying started off in a fabric covered taildragger (Aeronca 7AC Champ) and if was a hobby. But after three or four years it had morphed into a business tool. I rarely used my plane for personal use since almost all of my flying was for business purposes, often flying to a schedule set up months in advance. I really enjoyed flying but I sold my plane because I could never get myself to justify it as a hobby (like I do the bus).
All the pilots on here can probably appreciate how much it costs to aviate.