Cheating at Dungeons and Dragons (who doesn’t do this??)

So I joined a 5e game at 6th level a couple of months ago. Other players created a character with point buy, but I just wrote down big numbers instead. Instead of min-maxing, I just wrote up a sheet that was crazy powerful in every way. I.e.: +5 initiative rolls, +8 spell attack rolls, 18 AC without armor, etc.. One of the other players checked my stats because he wanted to see what was up and he saw that I had an 18 19 and 20 for my primary stats at 6th level with *no stat under 10*. He was probably thinking 'it is ludicrous how cool this guy is' but he didn't say anything. This week I used an eraser and a pencil to hack my sheet a bit more so now I have two 20s and a 19. All of this without leveling up. WTF, Why doesn’t everyone do this? Are they stupid?