The Ken Fisher ad that splashes across the top of Marketwatch for me uses $500k as their number. I think it's just a number to fish out clients who want to feel like big shots being high net worth and using "their guy" to manage their weath.
"Private Client" was mentioned and I know Fidelity gives you this designation if your account is over $1M. With this, you get a Private Client manager which means that when you call Fidelity for a generic question, you have to tell them "no, I don't want to be transferred to my private client manager because it'll land in his voicemail and I won't hear for 3 days what the answer to my simple question is". On the good side, it means that you get turbo tax for free. There's a trick to get not only online but downloaded versions. I did it this year just to see if I could get it. I was able to.
I work in a 3 building business complex. One building is chock full of Wealth Management firms. The question "Where are all the customers' yachts?" comes to mind. In the parking lot, I see on my lunchtime walk every day: Maserati Quattroporte, Maserati Ghibli, BMW i8, Audi S5, Porsche 911 turbo S, Mercedes E300 4 matic, Jaguar sedan (I forgot what they're called....something R). Makes me chuckle that they're "managing" to turn the wealth of their clients into their own to waste on big dollar cars (and I'm a car guy).