I definitely classify my crossdressing as hobby, it is an interest that I came upon thanks to the internet and my (at the time) girlfriend's desire to crossdress me for a Halloween party. If it wasn't for her wanting to do a good job on the transformation and searching on the net finding the Masquerade crossdressing group, I probably wouldn't have ever found this fun. It was a hoot dressing up for and being at that party. Got me going into more depth reading and looking at the pictures from that website afterwards. Then the searching by myself expanded to more internet sites and chats involving crossdressing then onto attending a Masquerade monthly meeting. I just don't understand why some folks can't believe that someone could stumble upon crossdressing via internet or other areas where one could stumble upon it (like kink fetish events) and think "Wow, that seems to be fun!" Look at what my sharing of outings in Victorian style dresses have created interest in some folks to try it, or Even my interest in trying the body suits and masking thanks to Docsherry sharings.
I do respect that many deem their crossdressing is not a hobby, but wish those same folks would return the respect for us that do it as a hobby.