i asked my friends that play league and they say its some kind of trial to make sure im not a smurf, and if i continue to play in ranked im going to get stepped on and loose every match.
The response to all the "My friends said X" things that get passed around is the same as what it was in the schoolyard when they gave you "health" advice. That is: "Your friends are idiots; don't ever listen to them."
That's not how placements work at all. To save you a half hour looking for youtube videos explaining ranked, I'll give you the short version. You have an MMR, it's the rating of how well you have been playing: who you lose to, who you win against, etc. When you go into ranked, you do your "placement games" which are really just your first ten games of ranked. If you lose, your MMR goes down a bit. If you win, your MMR goes up a bit. After ten matches, you get a tier and division that is representative of this. You, having not played ranked before, are a bit of a blank card, so your MMR got bumped a bit up towards the average, so you got a bit outmatched. After playing more, you will settle down into more even games.
This:
now theoretically if i loose all 10 matches i get placed bronze 5, if i loose 9 i get bronze 4, if i loose 8 i get bronze 3 ect...
This is not how it works at all. People can and have lost the majority of their placement games and get placed into Gold or Platinum because the win/loss ratio is not the sole determining factor of placements; it's a modifier.
heard about a diamond player purposely putting himself in bronze 5 and it took him 90 matches to climb to bronze 4,
That's bullshit. Plain and simple. What this is, is a story that get passed around by bad players to justify their beliefs that they aren't bad and it's all their "feeding teammates" fault they have the rank that they do and that ranked is all based on luck. It's an idea that has been proven to be false a hundred times over, not just by simple reason, not just by boosters, but also by the hundreds of "Bronze-to-Diamond" or "Unranked to Diamond" series and their like where players go from the lowest ranks to the top.
Anyone can simply watch these for themselves.