Speaking as someone who has worked in this industry, you appear somewhat misinformed about how high net worth individual (HNWI) typically invest. Large multi-family office firms pool investments from multiple wealthy individuals (usually investable assets of at least $5M or more) and can access private equity, real-estate deals, commercial mortgages and more. These firms manage multiple billions of dollars, which doesn't make them huge by any measurement, but they are more than large enough to access investment opportunities like these as well as create sufficient liquidity for their clients.
Wealthy individuals have access to investment strategies that resemble far more the philosophy of large pension funds than that of robo-advisors. (You can also check out Tiger 21, a sort of investment club for Wealthy people, they post their recommended asset allocations on a regular basis.) They also tend to be more focused on capital preservation and minimizing volatility than strictly beating the market. Their portfolios are typically highly diversified outside of publicly traded assets to accomplish that.
Finally, the firms that work with them offer significantly more for their money. Detailed estate planning and legacy planning, tax planning, corporate tax planning, and advice on charitable foundations and more.
While I do agree with some of what you are saying about how "advice" is priced, particularly when it comes to the mass market, there is definitely a point in the wealth of an individual where there couldn't be more points of difference between what people get in terms of financial advice.
Source: I've worked at a wealth management firm that dealt with HNWI for quite some time.
Edit: Just to add a bit on the different this makes for HNWIs
At the firm I worked at their client's biggest losses throughout 2008 were no more than 6-7% (after fees were considered), while at the same time being invested in assets that yielded nearly that much in cash flow through dividends, interest, etc. that same year. Since a portion of the portfolio was also invested in public equities (around 30%) and because these client's could easily stomach the markets considering their personal performance they were able to ride it back up without fleeing to cash like so many others did.
One of the problem smaller investors face is that in major market crisis situations almost all publicly traded assets take a hit as the mass market migrates to cash. If you follow the herd (as most obviously do or they wouldn't be the herd) you regularly miss out on the benefits of these market movements.