I assume that you're in the States and will be declaring your profits for capital gains or trading income to the IRS, I actually had the least trouble with US banks (3 of them), zero issues in fact apart from BoA asking me to fill in a declaration that I had earned no taxable income in the US, $1MM isn't really an awful lot of money there especially if you're in California or similar where my accounts are, personally I'd talk to the bank first and say exactly what you planned on doing and ask if they would have any issues with that, likely you'd want to have proof of your original fiat deposits to Exchanges or spent on mining equipment, plus of your trades as well, they could say you'd need to open a business account with them or something or they may just be cool with it being a profitable hobby sort of thing.

Which ever country you're in the above may be sensible and also to talk with a tax accountant to see the best way to do this from a tax perspective and perhaps the accountant could OK it with your bank prior to you sending any proceeds there.

For amounts > $1MM then the wealth manager route may be best, a lawyer shouldn't be needed at all unless you have failed to make tax declarations that you should have in which case you do need a good firm of tax lawyers to get your affairs back in order and to cut you a deal with the IRS, ie just pay some penalties and the back taxes to normalize things, PM me if this is the case as my wealth manager has already helped one US citizen with this, also I guess that you're not in a position to relocate to a jurisdiction that has no capital gains or income tax and renounce your US citizenship if you have that.