Ha, it was not my intent to start such a discussion on "is it ok to mock other people's bad habits", but I'll bite.
As MgoSam and Moustaches have stated, the goal is not to make myself feel better, but to confirm to myself why this whole frugality thing works: I'm not FIREd yet, so doubt comes regularly to my mind: "does this whole thing even work?". The "colleagues bringing a latte everyday" helps confirm it on a daily basis, it's a way for me to keep focused on my goals. Noticing all the "bad" habits from other people, and reminding myself "*this* is one of the reasons it's going to work for me, let's keep going".
I'm not mocking people or laughing at them, but I take some satisfaction and pride in resisting my own urges for instant gratification. Looking at other people whom I work with daily helps me building a checklist of things not to do: Expensive clothes? Check. Daily $5 latte? Check. A different pair of shoes every single day of the week? Check. A new phone every 6 months? check. Car commute everyday to compensate for a bad apartment decision? check. And so on and so forth. It helps me reflect on my own choices once in a while too.
Whenever I can, I discuss my frugality with colleagues, but most of the time I find closed doors. The most open colleague I got answered to me "yeah, it probably works, but I would have to give up things I'm not willing to give up in order to make this work". so, I'm not a complete douchebag about this, but I'd rather laugh about people's habits (including mine) than cry about it :)