MS killed Commodore & Gateway to get rid of the Amiga you love.
Um, no.
Microsoft didn't kill Commodore or the Amiga. The Amiga was never a threat to Microsoft. By 1985, DOS was selling exceedingly well as was the PC. The Amiga was never going to change that kind of momentum. Just like the Mac never put a dent in the PC momentum.
However, if Commodore has marketed the Amiga correctly, it could have found a much better niche and with proper hardware (chipset) upgrades they could have kept it there.
Commodore ultimately killed Commodore and the Amiga.
By the 90's, the PC killed anything that wasn't a PC.
I believe you can see PC and MSDOS sales on Wikipedia. When you look at 1983 through 1986 it is not hard to see how Microsoft made so much money.
-P