Yes, this is absolutely true! But if you make transit convenient without addressing the crackhead in the back, the first time someone tries it will probably be their last and we're back to "nobody uses it, so we're cutting the schedule to save money".

Fundamentally it's a competition between public transit and the alternatives (usually cars). Cities can influence both ends - make driving less pleasant by cutting road infrastructure, parking, add fees for driving into the city, etc and make transit more pleasant by improving schedules, cleaning, etc. I'm a big fan of the latter instead of the former because the former often pisses voters off and leads to a backlash that sets progress back instead. Unfortunately, the latter often costs more as well.