Cap Rate related question

[Blair Boan]

Quick question about an investment property I'm purchasing. Purchase price of 100k (cash) Rental rate of 800-950 (let's use 875 as a mark) $365 out of my pocket every month for HOA Taxes and Insurance and management That's $510 worth of cash flow every month. Cap rate is at 6.1%. Most seasoned investors say that's an ok deal. My question though, is with each year that passed and the more money I put in my pocket, does the cap rate not increase? Every year that passes, the renters will be paying me back my initial investment thus creating a higher cap rate every year. Is this even something to think about or is it always looked at from that initial investment. Thanks in advance. And for this who will tell me to go buy 5 houses with 20% down, I don't have two years worth of tax returns so that can happen until next season.