This isn't just an interest rate arbitrage, its simple interest vs compounding interest.

Compounding appreciation on 485k made more sense to me than ~8% on 10k in stocks.

Looking to talk to lenders/brokers to see how much I can get pre-approved for, compounding my knowledge I learned since I was in high school (2017) and applying it in real life.

What does 60 years of compounding returns do? 

You are compounding the situation by letting the tenant continue to live in your property.

UBTI is not generated from passive rental income.The Solo 401(k) grows over time with compounding of the tax-sheltered income, just like it would if it were receiving dividends on a stock investment.When you personally take a distribution in retirement, you will pay tax on the amount of any such distribution.

It's just that you can't compound interest. 

BIG tickets items are really important though; foundation cracks, structural issues, bowed walls, or uneven flooring.

Simply put $50,000 into a brokerage account and watch the 8% compounding interest do its' thing.This may sound odd to many, but I've worked in finance for the first decade of my career, and have continuously poured money into my brokerage accounts, building my nest egg (I'm currently 32).

Chris is also the one that explained to me the power of quickly compounding properties instead of buying live-in fixers that take a few years to finish.I agree with @Jeff White as well and will add that I enjoy getting my hands dirty with renovations but I can't wrap my head around how to rent out rooms and renovate at the same time.