Carseat confusion.

Ok so im not sure if this is a good place to post this question but..

So I saw a post on facebook about an 18 month old who passed away from napping in the carseat outside of the car. This has me worried about getting an infant carseat. Everyone keeps telling me I will want one for the convince of carrying baby around in it, but if it's unsafe to leave baby in it outside of the car or locked into an appropriate stroller how is that better? I was planning on baby wearing, but everyone kinda laughs at me and says good luck with that when I tell them. I'm confused and scared and not really sure what the best option is! Help please tell me your take on it.