We are in a constricted market cycle, low volume, strained budgets, high costs.

I met Kevin much later at a meet up through Subto and saw his phone notifications and how he has hundreds of people reaching out to him daily. 

I would say hire another you when your value proposition begins to slip (e.g. you can't stay true to your boutique goals because of the volume of work) or when the work is too much for you alone.  

The increased cash flow would make such a substantial difference in your daily life that not paying it off would be foolish.Outside of that, I can't see many reasons I would take a 15% tax hit to save 4% on a mortgage, which is really only effectively about 3-3.5% depending on your tax bracket.

Especially if you're doing enough volume to get good discounts on products.

With real estate, you’re owning a physical asset that’s less subject to daily fluctuations.

Have every detail spelled out, use an escrow account and daily updates verifying all parties are executing their responsibilities.

Valuation depends on your market = i.e. volume of STR supply and regulations. 

Have enough that after you buy the property you still have 6 months of expenses in reserves that you can use for daily living.

The current trading volume is mostly one crypto sloshing into another crypto, not billions of fiat flowing in and out per day.Like @Jerry Shen we too have a crypto position that's a much larger portion of our liquid funds than we feel comfortable with due to recent run-up.