Is it possible to rig a blockchain by controlling mocked >50% peers?

I just started to learn more about Bitcoins and how blockchain works. Basically, if 1 peer makes an unauthorized transaction in the blockchain, every other peer can validate that it's fake. How exactly does it work? If there are 100 peers in the network and 1 tries to fake it - it's easy for 99 others to detect it.

But what if you spawn 150 of your own peers (from the same computer?), that give the same faked transaction. Now there are total 250 peers, 100 claim it's fake, 150 claim it's not fake.