I purchase rental properties. when i was 22 i purchased a duplex rented out one side to cover my mortgage. I saved my money like i was paying a mortgage i did this for a little over 7 years. I'd get all my income tax money and invest in stocks. Never got real good at it but it paid off. I took a big chunk of my savings and started buying other single family homes and started renting them out. I now have 3 units i own free and clear and the original duplex will be paid off soon for a total of 5 units . now I'm saving that money to buy future properties.as i go the process should start happening faster. I'm 33 now i often bounce around the idea of borrowing money off my properties to buy more or just stick with the plan of saving the rent collected and buying future properties as the money and oppertunities become available
im a couple years older than you, but I have the same experience, except after i bought my first duplex, i just ended up buying condos/apartments (out of state) instead of houses bc of my own personal preference
like you, the cycle just kept going and I was able to buy units with straight cash......i pondered the same thing about taking lines of credit against my fully paid for properties and was hesitant at first, but ended up taking small LOCs, but only when I didnt have the cash on hand for when a desirable property unexpectedly went up for sale
otherwise, my portfolio has become a self financing vehicle where the vast majority of the $ invested came from the properties
my particular portfolio relies on the rental income instead of looking to flip for a profit since im focused on apartments
basic real estate investing, nothing complicated or crazy
im hoping to get into some commercial stuff soon and have my eye on a couple of small strip malls with great tenants in "up and coming areas"
EDIT: re: borrowing money against your properties
my good friend who works in commercial real estate educated me on how real estate pros look at their return. they'll look at "cash on cash" return....or the return you get on the ACTUAL amount of cash put down and payout during the lifetime of the properties' mortgages
instead of looking at the total return using the net rental income against the total purchase price (standard ROI)
since i focus on rental income return, i dont use Cash on Cash too much, but figured you might be able to use the info since you deal with houses (assuming you dont already know this)
of course you have to weigh the costs associated with the HELOC you may get.....but basically if your cash on cash % is high enough to justify the interest you'd pay on the HELOC,, then go for it!
here is a useful link
https://www.investopedia.com/terms/c/cashoncashreturn.asp