If you load it full of expensive software that could increase the value significantly.... how you get this software is your choice
This is a terrible idea. Adding a bunch of pirated bloatware does not increase the value of a machine. In fact, it is probably one of the biggest red flags for buyers in second hand markets.
It also assumes the buyer is an idiot. Anyone person, that is not up to no-good, will wipe a hard drive they purchase and do a fresh install. In fact, not doing so is an invitation to deal with lots of problems down the line. It's thoroughly idiotic not to do a fresh install of a computer you buy that isn't from the dealer.
Nobody will pay for something that would be immediately erased. Even if they are an unsavory software license pirate, they certainly won't pay extra or a premium for pirated bloatware that they can pirate themselves.
Loading up software on a computer is the red flag for:
A) Undisclosed problems with the machine that the seller is trying to cover up
B) Evidence that the seller is trying to slip in malicious software
C) The machines resale value is nowhere near what the seller wants.
D) Evidence that it's all pirated crap.