SASless,
I don't think that individually, your big diesel truck makes much of a difference. I don't think the EV that I drive and charge with the help of PV panels on my roof makes a dent either. It is, however, an issue of scale. The millions and millions of diesels do make an impact as does the slow but steady slide toward EVs. Before you say " "but what is the impact of making and disposing of those batteries and PV cells etc"., I understand that there is a price to be paid. In the long run, based on what I've read on both sides I think moving away from fossile fuels is good for all of us and that environmental harm and health issues will diminish as they did with reduction in smoking. Same with the use of plastics. Do I deny your right to drive a big truck? Certainly not. Will I try to convince people that unless you really need a large vehicle ( and you may need yours, I know not) that there are advantages to driving more efficient ones? Absolutely.
I have no idea if human life may become extinct. If we do it may be for reasons unrelated to what we drive. If, for example the native pollinators and cultivated bees are struggling to survive or actually are reduced to being ineffective at filling their niech it may be a bigger blow than greenhouse gas pollution. How many people will say "gee, we didn't see that coming" despite 20 years of warnings by bee keepers and ecologists.
If it matters not to you, well than there we are aren't we? I recently had the opportunity to visit Tokyo and yes I flew on a big smelly 787. The fascinating thing I noticed after a week of walking and subway rides was that in Japan or at least Tokyo, people seem to understand and accept that you do certain things for the common good much more so than in the US. I'm not so much considering this on the local scale where efforts for community well being are more noticeable in the US. I'm speaking of national scale. It made me take a hard look at how we handle homelessness, mental illness, healthcare and simple day to day interactions. I am not without fault in being selfish but I try to be aware and look at the bigger picture when I can.
In closing, i will say that the biggest problem we may have is our feeling of exceptionalism. Is the "Western Nations collective" ( what ever that is)really the best ever? If you want to wave the big foam rubber number one finger, I say have at it. Most of our issues revolve around thinking our tribe is better than your tribe. Over and out.