But statistically speaking, investing in a pre-revenue startup is extraordinarily risky.

As such, a LLC is not required when using a Solo 401(k).As @Mark Davidson indicates, there are strong protections between you and the 401(k) in both directions, but that is not what you are asking.If the Solo 401(k) will have a variety of holdings and you want to create risk segregation internally within the plan, it is possible to use vehicles such as LLCs to do that.  

https://therealdeal.com/miami/2020/07/16/javier-cervera-jr-buys-apartment-complex-near-miami-international-airport/ How did you find this deal and how did you negotiate it?

Invested around $4K in some minor upgrades and improvements and within the 1st 2 months generated almost $10,000 in Revenue!

He was a millionaire by age 25, started his Youtube channel to share his stories and now makes $250k to $350k per month in ad revenue just making videos in addition to selling real estate.

You need to properly account for true costs and revenues.

- Revenue management is basic and I’ve had trouble with multiple bookings being left out of reports.- Customer service is not as responsive and prompt as I’d like them to be.

I would recommend purchasing a data set from Mashvisor or AirDna so you can see actual revenue numbers in the area. 

It's annual Net Revenue is $216kWhat's the best way to present 100% seller financing ?

I am 30 years old, married with 2 children, 1 on the way, and work for an international bank full-time as a business analyst.