98% of laptops, notebooks are not ment to be gaming rigs. The 2% that are, are very high end and some that are made to be gaming laptops. And most of them come already with two different GPU's in them.
And of course you can spent around $2000.00 or more for those types of laptops and also when you go to upgrade them it is goind to cost you anywhere from $1000.00 to $2000.00 or more just to upgrade a GPU.
Like stated above. Desktops are the way to go for gaming. A lot cheaper and the upgrads are not going to kill you in price. Just though I would throw this in and good luck to you.