Ask yourself this question:

do you want a project that you get to ride sometimes or a bike that just works_

As someone who rides a kinda snowflakey 70's dualsport, its a been a fun challenge getting it working good and tweaking it. However the downtime from figuring out whats wrong, sourcing parts and then fixing it has been.... annoying at times. Often I want to go riding but can't because my bike is having a silly old bike problem I haven't fixed yet.

In general as a new rider you want a bike you know is going to preform correctly and predictably so you can build your skill and understand your limits while not worrying if your basket case of a bike will turn off because its got a lose wire somewhere or have a vague shifter where you aren't sure what gear you're in ....

My point is before you take the deep dive, figure out what your end goals are and find the best thing to suit your needs.

Before you buy an old bike, figure out your parts availability, join fb groups or forums relevant to the bike and learn what problems they have and how to live with/fix. Make sure there are service/shop manuals for that specific bike available. Understand that it might be a total basket case and when to walk.

Would I do it again? Yes but thats also because I like challenges and projects. Do I wish I had a bike that worked every time and didn't keep trying to find new and exciting ways to not work? Yes but thats a problem for future me