How do you know when development wasn't test driven?
Fixing the bug takes 30 minutes, fixing the tests takes 3 days.
Do I think that developers who don't do agile are worse developers than I am?
What tool do you use for product management? is a question as stupid as asking What tool do you use for software development?
Whatever you decide to learn do it one chapter at a time.
Do I think that developers who won't do agile are bad developers?
No but I think that our ways of working diverge so much that collaboration is practically difficult.
A daily walk is more important to quality than an uninterrupted session or flow.