Why are computers so strong

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75 years of algorithm research, coupled with advances in computer hardware/speed.

computers can read your mind and know what move you're about to play

They're not good at the chess that humans play - it's something else when a CPU does it.  Witness:  there are relatively easy problems that no current generation computer player can get right / solve, whereas humans will get the right move pretty quickly... (see https://www.chess.com/forum/view/general/a-chess-problem-that-computers-can-t-solve for example)

The thing is - you don't win at chess.  You merely lose softer and/or slower than your opponent.   Computers are really good at not making calculation mistakes.   They only lose at not evaluating positions correctly, and the best computers are just as good as the best humans at that.   So they have the edge in most games - but not all. 

There are actually special tactics you can use to get a "not all" game and there was a sort of cat and mouse for awhile where each generation of computers bred a new set of "anti-computer tactics", which then get fixed in the software, etc...   now we just sort of accept that computers are generally stronger.

If you are not an elite player who almost never blunders, the fact that the computer literally never does means you will 100% lose.