Help understanding equity and net worth roll over to "trading up"

[Josiah Sia]

Hi there BP friends. Been reading Brandon Turner's "Rental Property Investing" book and I got stuck on one of his examples. In chapter 5 he lists 4 example plans on how to use REI to build wealth.

I'm confused about his 1st example.

Below is an excel document I used to map out his 1st example plan. I understand the #s aren't what matters and it's the math and concept, but I'm having a hard time understanding the concept. Particularly year 8 when he sells the 24 unit apartment and buys a 75 unit apartment.

He mentions in the book that in year 7 he takes his equity, which is his net worth - about $100,000 for sales expenses, and that he has about $650,000 to put for a down payment on the new 75 unit apartment. 

My question: How does he get $650,000 out to put towards the next trade up 75 unit apartment? He has $172,800 cash saved up. That makes sense. What doesn't make sense is how he calculates the rest of the $ to put into the down payment. I'm a complete noob and I could just be missing an easy process here, but I thought equity doesn't exactly translate in "money in pocket" per se out once you sell. So equity has built up to $526,000 on his 24 unit apartment because of the tenants paying the mortgage, appreciation, and for the down payment he put down on it. Right? But selling the 24 unit apartment doesn't just get you $572,000 cash in your pocket does it? 

Aside: I feel like this scenario isn't too far off a "perfect model" that can be easily done. I'm just having a hard time picturing a 10% home value increase by doing some minor repairs in the 1st year of ownership.

Any advice or help for this REI noobie would be much appreciated. Thank you!