They are keeping most of their assets in BTC. Take a look at some of the richest like the W twins. They aren't turning anything to fiat.
I don't know how the millionaires in the UK are doing it, but If I had a couple millions I'd consider moving abroad and buying a piece of land on some tropical island, away from the wars, migration, pollution and politics.
Sporadic in time intervals. The safe amount is probably up to £11k per account from the same source per year. That doesn't mean you can't send more. Chances are you won't be flagged, chances are you will be but no authorities will take action, or they will but only to check if it was included in your tax report. I wouldn't worry too much.
If you were really scared of the banks and authorities and at the same time wanted to go the legal way (money to a bank account, reporting income) you could always set up 2 or 3 separate bank accounts and divide your coins between 2 or 3 exchanges. Then sell below £11k worth of coins on each of the exchanges and move it to your banks. Withdraw cash and put it in a deposit box or a safe. Note that this is an overkill option for those who don't trust banks (like I do after the Cyprus bailout) and want to have total control of their money.
Ok im getting to understand more, do you know which exchanges allows withdrawals to multiple bank accounts?
Just to clarify it is £11k limit per year? If so that sucks if I was a bitcoin millionaire who like to cash out.
If only more places and shops accept bitcoin so no need to cash out you know what I mean. Like I can walk straight into a lambo dealership and pay directly with bitcoin.