At that amount, is private banking really worth, compared to using a regular bank account, and a regular brokerage account and, if you need support, paying an independent investment consultant to do investing?
Yes
What does private banking get you that is worth the extra costs?
I can imagine that private customers have a much easier way to get cheap $$$ using their assets as collateral. So let's say you are a DIY guy, would there be a DIY way to get a cheap loan offering assets as collateral outside private banking (but, possibly, inside your regular bank account, if needed)?
Other advantages of private banking, beside having the guy call you to tell how much in red your investments are?
See my post below post from March 2021:
Because they actually provide wealth management services which contains assets protection, inheritance planning, white label fund creation, life insurance wrappers, offshore structures, trusts etc. This on going advice is worth something. You can also get personal access to some of the best fund managers at investment events they organise and also client networking events. You also get preferential access on IPO's etc as many of these banks are the book runners for the IPO. If you have offshore companies they will take these and in fact offer you them as part of wealth planning. Btw I bank with every name you mentioned except DBS.
Their direct investment advice they give in my opinion useless if you know the basics of financial markets and products. But the advice I get on how to structure my wealth and where to book my assets etc for succession planning is invaluable. You do not get this with a broker. You cannot even send your portfolio to a thirdparty with a broker which you can do with a private bank. The fees they charge for all services from brokerage to custody etc are negotiable. You can ignore whatever they write on their website if you have more than $10m to invest.