If you don't mind having your money tied up in a warranty, it's not a bad option. I bought one for my 2020 Model S thinking I'd keep that car for 6 years also, but changed my mind when the new Refreshed MS came out and I discovered my 2020 was worth a premium on the used market. Tesla will fully refund the warranty cost if you cancel it at any point during the first 4 years, so there's not much risk in getting it now at the discounted price, and then reevaluate when you get close to the 4 year point whether the car seems reliable enough to forego the warranty or not. If you sell it, it can be a nice selling feature or you can cancel it and get a refund.
Most people will say the extended warranties are a pretty bad investment overall, and that you'd be better off putting the $4k into TSLA stock today... I can understand that philosophy (my TSLA stock has done REALLY well these past few years, as I'm sure most of on this forum appreciate)...