Buying used makes a lot of sense, especially for commuting. The design of the bicycle was basically perfected in the late 1800s, anybody trying to tell you different is a fart boofing Tesla fanboy with an engineering degree and zero cycling experience.
(Admittedly, I ride a carbon frame road bike with electronic shifting, not because I'm a shit sniffing engineer with a hard-on for Musk, but because I'm a middle-aged man with lycra for brains).
Keeping thieves away by never cleaning the bike reminds me of the old bicycle touring strategy of hanging sweaty and unwashed clothes to dry from your handlebars when parked. Bonus theft deterrent!
To be clear, having an engineering degree is cool – it's the very specific (but all too common) type of engineer that wants jerk off into his own mouth when he sees a Cybertruck and organically follows Elon Musk on Twitter, that is lame and has a lot of bad ideas, sometimes about "innovation" of bicycles.