We sold our Irvine house to someone like that (except they did get a mortgage). It was an awful experience I wish on no one.
He kept making offers (starting with ridiculous low ball offers) and came in with threats like, "I'll just buy the one next door for $250K less than yours and you will NEVER EVER see even $1.8 Million for your place. You'll have to beg to sell to anyone. Only Chinese can buy, stock market bad, no Chinese can get money out of China, lucky you even got my offer, blah, blah, blah.
Luckily we had multiple offers so we could play that against him and he liked our house and not the one next door.
Our realtor said he wants "deal" and I said "it's already a deal, priced $50K under the last sale which was against a road and no upgrades and a T intersection which sold a couple months earlier. Finally I got majorly PO'd and raised the price and said NOW he's got a deal!
He finally came up, we took his offer of $20K less with no other counters and oh no............. that wasn't his REAL offer which included a $10K deposit (fully refundable of course on a $2 million home), contingencies up the wazoo which basically let him walk for no reason up till closing, long escrow instead of his promised short escrow (which is why we took his offer and not the competing offer), on and on.
We had to send demand letters for him to keep his end up several times, had to give him cash off the price for stupid crap like one shutter was cracked on one slat which was fully disclosed and were pretty sure he'd try some further "blackmail" to get it closed till we did close.
He didn't move in for a few months and then said he wanted to return the home and would sue us because a toilet backed up if we didn't take it back. LOL!!!!!
Unfortunately for him we pointed out we already moved and the bank wasn't giving us a loan for his house since we already owned this one and in THIS country we don't just change our minds and give the house back after escrow closes and he was free to check out the cost to sue us over a non issue which could be fixed by any plumber since there was no plumbing issue in that house the entire time we owned it and maybe they should learn to operate toilets in THIS country.
Amazingly arrogant and threatening and we never even met the guy and it wasn't even a cash offer.