If it was that profitable then it would be cheaper? That doesn't even remotely make sense in the most superficial ways. I don't even understand how you'd think it does.
Maybe if there were infinite housing options? But housing supply is extremely low in the US in large part because larger corporations are buying up huge swaths of housing and turning it into rental housing... Because it's really really profitable. And since supply is low and prices are high, it's not possible for most renters to buy houses. Nobody rents because it's cheaper overall, they rent because you don't need tens of thousands of dollars upfront for a down payment, plus a great credit score. That is, unless you're in Boston or the like where you must pay first months rent, last months rent, a security deposit, and a realtor fee generally equal to one months rent, meaning for that relatively reasonable $3k 2br apartment, you need $12k upfront to move in. So why don't they just buy it? Because buying a 2 or 3br market rate flat in Boston or the surrounding municipalities would cost maybe from $700k to $2m. The further surrounding areas are only slightly cheaper and by the time you hit more affordable places, your looking at a 90 to 120 minute car commute each direction.
You either don't understand the math or you're not interested in understanding the math and just want to justify gouging people. Like I said, I own the exact type of building that most landlords own in the urban northeast. In fact, it was an absentee landlord rental building for decades and hasn't structurally changed since it was. I know EXACTLY how much it costs to operate this building, and how much labor it takes. That hand-wavy "but it's so expensive and takes so much work" garbage doesn't work on me. It's not labor-free and it costs money, especially if a roof needs to be repaired or the like, but that's true in all businesses and if you don't prepare for it well enough to not be a disaster when it happens, or you buy an instanely unreliable and maintenance-heavy building, that's not your customers fault. Even in our flat-roofed old timber-framed triple-decker, our very healthy and responsibly funded major repair savings and building expenses fund (roof repair, insurance, snow removal, water damage repair, etc) takes in a little over 5% of what our rental income would be in this fairly inexpensive market, and aside from the gardening and cleanup in the courtyard, we contribute nearly no labor outside of our own units.
There's a culture of entitlement among landlords, at least in the US, that completely skews their understanding of what they deserve for what they put in to something. You show real plausible expenses or labor that I don't have in my 19th century timber-framed building that most other landlords have, then I'll happily change my perspective. I've asked for that every time I've had this conversation but it just doesn't materialize.
You want to see what a lot of labor and expense for the amount of profit looks like? Look at the Eater article where the owner of Mei Mei in Boston details her P&L.