I'm going to make one assumption. This individual has 100k to start (they need some money to keep 8 flips going in a year).
Technically, if someone does 8 flips a year, they'd be hit with high taxes and would probably end up with about the same as someone with a 100k-120k a year job.
After the 10 years, that person has nothing left but maybe some decent money in a retirement account. So at the end of the 10 years, they still need to keep flipping to keep eating.
Lets say the buy and hold guy uses hard money and leverages his 100k to keep from pulling as much out of pocket. They should be able to buy 20 houses (4 per year) in 5 years. I'm on pace for that now and I didn't have 100k to start (14 houses in 3 years).
If the investor took all his income (300 to 400 a month) and used it to pay down their houses, they would probably have 5 or 6 of those early houses paid off.
So at the end of 10 years, that buy and hold investor would be generating about $9,400 per month and could actually retire from their real job. (350 per month x14 houses =4900/mo, 750 x6 paid off houses = 4500/mo). That $9,400 is mostly tax free from depreciation so that would be like a job making 100k a year if not more.
Add in the appreciation and debt reduction that those 20 houses are now going on top of that to have going forward and I don't think this would even be close.
i.e. after 10 years, those houses might have gone up from 100k to 125k. While the loans might have gone from 75k apiece to 60k (assuming payoffs of 6 and paydowns on the other 14).
2.5 mil in appraised value with 1.2 mil in loans.
So to me, this is an easy question to answer. After 10 years:
1) A flipper will have a nice chunk of money in a retirement account but will have to keep flipping to eat.
2) A buy and hold investor will be able to retire and will be making the equivalent of 100k per year with about 1mil in equity in their homes.