well the idea of a studio used to be a commercial business venture there used to be return on the investment you'd buy mics, preamps, cables, stands, instruments, etc and people would pay you to use them and your services which over time would ideally land a profit.
as with most things it's about being financially responsible. Most things are expensive. Just be aware of what you have and live within your means if you aren't earning money from the investment and it's simply a want DONT BUY IT!
I'm not sure what you are hoping to garner as building a simple home studio can be done very very cheaply especially considering what trying to build a setup would've cost about 20 years ago.
For heaven sakes you can get a decent enough mic, recording interface, monitors/headphones, and software all well under $1000.
20 years ago you'd be lucky to get a decent mic, 4 track cassette recorder, etc for that price and you got no where near the fidelity or features you do today.
When you invest in a home studio you are investing in convenience rather than paying an experienced sound engineer with all the gear, know how, proper recording environment you build up your own. So over the course of time you save money vs going to a commercial studio to record at $30+ per hour (I used the lowest local rates I knew of with that).
There really isn't much money to be made in the music industry these days. The amount you can spend to produce albums, or spend doing a tour seldom is more than you pull in gross from doing such undertakings.