I owe almost my entire existence to DOS.
If you survived DOS, you became a PC gamer. To have laboured in the command prompt mines was to become someone who is only slight fazed by the many technical problems and complexities which blight PC games to this day.
People who run a mile from PC games do so because they didn't go through that trial by autoexec.bat fire at an early age, so never learned to discipline of having to work to make a game run well.
DOS really was a game unto itself. You learned skills and strategies, you learned to adapt, you learned to learn more, and you learned to figure it all out by yourself, because there was no internet to ask. You learned about memory and you learned about file structures, you learned about ports, resolutions and colour depths. You learned how to make games better, how to make them tailored to you, and what it was they were made of. Pity those who never saw this, who go to pieces if they have to do anything more than click an icon - and who don't even realise how much complexity and wizardry lies under that icon.
Because I survived DOS - and learned DOS - I became and remained a PC gamer. As well as getting the accursed things to run, I learned how to hide them, and that I played them, from parents who tried to keep me from them for fear I'd fail my studies. In turn, that learning lead to a job on a magazine, and then to this.
I wouldn't go all the way to saying DOS made a man of me, but it did make me willing to keep chipping away at a problem until it was solved, rather than freak out or call in others to do it for me. Thanks, DOS. ThOS.