Ying,
Here is what worked out for me. I am retired at 33 years old. Writing you from beautiful Sun Valley Idaho, on a ski trip. Disclaimer: buying houses all cash is not the smartest way, this is just what I did at the time. My journey was a marathon, not a sprint. Started in 2013 with the hack, and the rest of the journey is below.
I house hacked right out of college. Bought a 3 bed in Manayunk with PITI @ $1000. Rented the two spare bedrooms to my friends for $500/month each. I lived for free. Built in a 4th, smaller bedroom. By then I rented that for another $500 and as roommates changed over, I upped to $600 for the bigger rooms. I was making $700/month + saving around $1000 in rent. So I socked away that $1700/month for a while and bought a house for all cash in brewerytown. Rental #1. from a wholesaler.
Fixed and rented #1 for $800/month (small and not a great house). Pulled a HELOC on #1 and used that to buy Rental #2, all cash again, wholesaler. #2 rents for $1450 a month. I guess I just like showing up at closing with a briefcase full of money. Rents from #1 and #2 were used to pay down my HELOC quickly to avoid interest.
Rental #3 came from a wholesaler. $21k cash purchase (used that same heloc, AKA SOMEONE ELSES MONEY). Easy rehab. Rents for $900/month... im now I'm at $1700hack + $800 #1, + $1450 #2 + $900 for #3 and I'm making $3400/month after PITI but before any expenses. Not bad.
Rental #4 another all cash deal. $35k... What was I doing!!!. Squatter special 3 unit. One family was living in all 3 and running an illegal daycare out of it. I came in with a lease agreement and an eviction notice, their choice. They signed the lease :) ... Triple net lease for $900/month. That means I FIX NOTHING AND PAY NO BILLS.... $4300/month Not great but not bad for a young person with a full time job. #2-4 were all bought with that same HELOC. Just kept recycling those benjamins.
Rental #5 First BRRRR! 3 units. Hard money 90k purchase, 80k Rehab. Cross collateralized my free and clear properties to secure the loans with no money down :) Maybe buying all cash was smart? At the end of the day, COVID happened and my refi did a drive by appraisal and I got screwed. Had to bring $20k to the closing table to get my final mortgage. PITI was $1200. Rents for $3200 total, so that another 2k for me.... we're at $6300/month now.
#6 and #7... due to low interest rates and my income I bought two homes for around 100k each. They rent for $1200 and $1100. PITI for both is $1100/month. Thats another $1200 for me and now I'm at $7500/month income after debt servicing and taxes.
This is when I quit my full time job. People here might say, $7500/month is not great. But Hey. I'm fishing and skiing every other week :)
Good luck. I hope this is helpful or useful in someway!!