Sure, not driving can make your world smaller. It limits job opportunities and logistics around traveling can at times be more difficult.
Setting up your life so you're relying on driving for everything and then being in a situation where it's not possible can also make your life smaller if you haven't developed the skills/confidence or don't have available alternatives - and everyone who drives is an unlucky moment away from being in that situation, even if temporarily.
Personally, I feel a bit lucky having hated driving as a teenager, chose to build my life so I can merrily live without it, and then became medically unable to drive. There are a few trips I'd like to do that are harder to plan without driving and some jobs that looked interesting I can't do because of it - and I accept that as part of my life. Few can do everything they want.
Also - I find not driving gives my kids more independence compared to many others I know where their kids only travel if someone is driving them. My kids have been here, there and everywhere meeting friends and doing activities - and they can do it without waiting on a parent to be available because their father and I chose to live somewhere that they can do that. Where I am, that's fairly normal.
Sorry my friend was just an example, the thread was about having more independence and opportunities if you are able to drive etc
Yes, some opportunities require being able to drive, but as others are showing, your friend is a poor example of how limiting not driving is for most who don't.
Plenty of people have a lot of opportunities and can make far more independent choices than your friend without driving. I've immigrated countries solo without driving. My DS1 gets flown out by his employer cause he can do magic with a ship engine - he doesn't drive, and even if he could in the UK, he couldn't where he's been sent to most of the time so his employer books and pays for all the transport. DD2 is looking forward to and saving to drive - but in the meantime, she's working a job she loves most of the time and traveling all over with friends entirely with public transport.