At the age of 64, I still have a lot of strength goals to achieve on my bike. I hope I'm always reaching out toward some goal. That doesn't keep me from enjoying the nicest bike I could afford. I bought the best I could back 16 years ago, have spent even more over the years in upgrades and keeping up-to-date components, and don't regret it. I think if you start with the best frame you can afford, in the type of bike you figure you'll be riding today, tomorrow, 5, 10 and 20 years from now - you can do the component upgrades over the years to come.
I was just taking you literally when you posted your opening statement,
"I have a tendency to usually get very immersed in my hobbies. I love to mod and spend money. What's interesting with cycling though is it's such an expansive sport that it feels like a black hole of modifications and custom builds."