Well residual = salary you pay yourself, and yes you can put away a large chunk, but you'll never catch up to a guy who just walked away and sold his company for 10 mil. Well not in single life time.
i.e. lets say your friend gives himself $250,000/yr and he grows that by 15% every year and then gets another 10% as a return on his investment, and then lets compare to a guy who just got his check from Google and put it in the same investments to get 10%.
So I threw this into excel:
Row 1: $250,000x1.15 <--this is his company growing at 15%, so he can afford to give himself, a bigger payout(15% more per year)
Row 2: $1,000,000x1.1 <--this is his 1 million he currently has saved, gaining the 10% from investments
Row 3: Sum of 1+2 <---both numbers combined
Row 4: $10,000,000x1.1 <--the guy who took the 10 million, and invested it
After 20 years:
Guy who is still running his business 24/7, growing it at a magnificent 15%: $10.8mm
Guy who is doing absolutely nothing, or started another company: $67.2mm
Now I'll grant you that the guy who is still running his business, also has his own company that is probably worth more than the 57 million difference. But to get that, he has so far worked non-stop for 20 years.
After 40 years:
112.2mm
vs
452.6mm
After 60 years
1.4bb
vs
3.0bb
After 80 years
19.986bb
20.484bb
So as you can see, it'll take him 81 years, before the guy who wants to keep his company gets the same amount of cash, as the guy who became millionaire at the age 30.
Thats the whole point, you sell your company as soon as you are offered a large enough chunk of money, so that you can start investing it. The whole "the rich get richer", is possible because money makes money. And that 10% is pretty average, usually possible even if you are risk averse.
And even if the person is COMPLETELY risk averse, and put that money into different ING Savings type companies, which give you like 4.7%, it'll still be 39 years before the residual guy catches up.