Re-read,
He actually said that if you have $10K worth of BTC then risking $500 per month would be good, instead of putting it all in Coinbase.
He didn't say that it would be 6.5% gross per month.
In here 6.5% is the annual interest rate
Good point. The thing is, amid all the nonsense in the OP, the offer mentions USDC, while hes talking about Bitcoin, or its clear that the offer is for one month, even though he says:
If you have $10,000 worth of Bitcoin it's smarter to risk $500 every month for this 6.5% gain.
I think it's pretty normal such a misread.
Actually they won't give a monthly 6.5% bonus, this is a 6.5% APR (Annual Percentage Rate) which means they will give 6.5% profit in a year but this campaign will run for one month. They are advertising in such a way so that everyone thinks it will give 6.5% profit in 1 month which is a yearly 78% return. I don't think an exchange like Coinbase will make such a big loss.
It's a common advertising tacticin fact, like banks that advertise a 5% rate, but if you read the fine print, it's only for the first 4 months, and after that, you get 1%.