Darned good question.
I’ve asked it of myself for about 6 decades – ever since I discovered that things you like to do are a hobby and things you don’t like to do are a chore. I’ve tabulated the former and latter and I’m happy to say that the first outnumbers the last – so I have a credit in my fun account.
How do you know when a mere experience or activity becomes a hobby? When you devote more than a half hour a day to it – this can be accumulated over a week to 3.5 hours or more and spent all in one go – attendance at a hobby club or social circle, for instance. The most it can be accumulated is a month – 14 hours – and then it must be discharged.
Can a chore be a hobby? Only if you are very lucky or very unfortunate. That old saw about doing what you love so that you never work a day is somewhat true, but like all old saws gets rusty and loses teeth eventually. I know people whom I suspect have never worked a day in their lives because the thing the dearly love to do is sponge off others. That’s not a hobby – it’s a crime.
Can hobbies be fluid? Yes, and if the fluid you choose is brandy, don’t expect to get much done in the evening. But you can change from one hobby to another quite legally. It is not so easy in practical terms, however.
Hobbies cost money, time, and social effort. If you design to change, you are going to have to do something about the past expenditure you will be foregoing and the remnants of the thing. You may have left over equipment, projects, and people who are still valuable… And you’ll find it hard to give up valuables.
The thing to do is to meld – make one hobby flow into another. Take some of the gear and investment in whatever you did before and make it do now. Carry people over from one social group to another – the ones you value – and you’ll find that they are still a delight.
And occasionally you can return to an abandoned hobby and take it up again – it will be all the sweeter for the rediscovery.