If they are changing jobs, they need the new job first and you need to paychecks or offer letter with salary or maybe even the first two paychecks at the new job, depending on their level and income.Ask them about deposit and rent. 

Consider all the things that could go wrong and see if the lease addresses them: unauthorized pets or tenants, early termination, security deposit, lease violations, late rent, eviction, lawn maintenance, parking, etc.5.

Put down deposit, lease isn't signed. 

They will try to run 2 kitchens and that can mean clogged drains in your wet bar kitchen.Be sure there is personal recourse when you need to sue them for $40k in repairs above the deposit.

If you're living in it now, you'll probably be required to have a signed lease in place as well as proof that first month's rent/security deposit were collected in order to get a DSCR loan (they're business purpose loans and don't allow owner occupancy).

So it was managing a risk rather than for profit.I’ll defer to others on mortgage paydown versus investing, other than to say that you may want to consider how far towards your next house / investment property deposit you are with the money instead of recast / investing.James 

Other examples of sketchy things Elon has done are his "FSD" technology claims being false (was under investigation for this I believe but the DOJ will probably drop that now), engaging in stock manipulation and making no secret about it ("Funding Secured"), the 2019 robotaxi event where he said they'd be on the streets in 12 months (still waiting), the recent Optimus robot event where the robots were supposedly AI but were actually controlled by humans with remotes backstage, taking deposits 10 years ago for roadsters that were never made, inflating Tesla range estimates, falsified displays and corporate orders to talk owners out of bringing vehicles in for corrective service, highly questionable government contracts... there are so many examples that are arguably unadulterated fraud. 

Or do they just want to sign an agreement to move out in 30 days and you'll give them their full deposit in cash on move-out day, if they leave the place clean?

I like the one that requires payments to be deposited in an escrow account:New York state law requires that consumers receive a written contract for home-improvement work that exceeds $500.

All you are going to do is put a deposit on it, hold it, and then try to resell it into a much smaller network than it is on now.