Alright, there's sooo much here I could address so I'm just going to pick out a few points and provide some commentary. Obviously we're too far apart on the spectrum to really change each other's minds 180 degrees so I'm considering this more of a discussion/exchange of ideas than a debate where I'm working vociferously to change your mind.
At the start of the transaction, the lender has whatever he's lending out and the borrower has nothing. At the end of the transaction, when the lease is expired or the loan paid back, the lender has what he started with plus the rent or interest payments, and the borrower still has nothing, minus what he paid in rent or interest.
In reality it's a little more complicated. The lender is taking a risk with the borrower (this is true for both rent and interest) and also the risk isn't just with the borrower it's with many extraneous factors. I feel like socialists/Marxist don't have clear account of risk which is really, really central to capitalism.
If we're just talking a normal loan the borrow could just run off with the money, or inflation could become such so large that by the time the borrow repays he's actually paying off less (in real terms) than the original amount. If we're talking about a renter here we need to take into account renovations, trash removal when the renter leaves, problems with facilities, replacing older appliances, and a billion other factors that could arise. The landlord could be sued.
The landlord needs to worry about constant upkeep and the highs and lows of the real estate market. Landlords and lenders can very easily lose money and I never see this risk mentioned when this point is brought up by leftists/marxists/etc.
That's how it's supposed to work in a truly free market, wealth goes to those who are doing the work, and if you slack off you lose it.
Not necessarily - maybe their investments go up. I actually find some capitalists tend to agree with you here (i.e. they really stress hard work and how those who work the hardest make it to the top and deserve it) but this just certainly isn't how I see things. I mean don't get me wrong - much of the top earners do pull insane hours, but risk tolerance again can definitely play a role. I don't know about you, but I would never want to live in a world where the ultimate determinant to making wealth was how many hours you worked. It would be like slavery. Investment helps you escape this.
I don't know what you're going to think of this, but those who don't work don't necessarily deserve to be poor and those who do work long hours don't necessarily deserve to be rich. Would you agree? "Deserve" has a place when it comes to morality and justice, but we need to be very careful with it when it comes to economic status.