Newbie looking for guidance - buy and hold strategy

[Kyle Sprague]

I'm so new to this world and looking forward to the immense growing that will take place.  Here to be a sponge and apologize if this question is silly to most of you experts, but that's why I'm posting, to hopefully learn and absorb from all of you pro's!  This is my first post and just signed up on bigger pockets, inspired to follow this passion of being a rental property investor.  

Anyway, I'm deciding how to enter the game and one of the ideas I have been juggling about is how to initially replace my current salary through cash flow investment, so I could focus on rental property buy and hold investment full-time while also getting some work-life balance back in my life from my 14 - 15 hour day salaried position.  My question revolves around this and I want to use an example to set it up.  

Just to dumb this down a bit, let's say an SFR buy and hold cash flows $300 per month. If I started with 1, I would need to scale to 10 before I could quit my current job and replace my current salary ($3,000 cash flow). I make more than this now, but to comfortably pay the mortgage on my current house, etc. I would need to cash flow $300 on 10 units at least to sustain my current lifestyle. This could take years, given that I am absolutely starting fresh in this game as a whole and have so much to learn. That leads me to my question. Why not just buy a portfolio of 10 SFR buy and holds as the initial investment right out the gate? What are the cons to this? What holds people back from being able to do it? Why wouldn't everyone be doing it if it were that easy? Why would 95% of REI that aren't corporations start small and scale large if it were that simple? The answer for me is "I don't know". It seems like only the bigger fish are able to do this based on money in the bank, but if you're using private lending or hard money lending, etc. why wouldn't someone just go that route to start vs going one by one over the course of multiple years - just go big? I should also mention that I have nowhere near the personal down payment it would take to buy a portfolio of 10 properties, but assume that could all be obtained through the different funding strategies out there? Apologies again if this is the most ridiculous sounding question of all time.