OP, are you the guy that had the Z4 and mentioned it in like every post he made for about a year? Because if so, they're acting like that because you're being insufferable about it and trying to humblebrag just like this thread so they're probably poking fun because you're acting hoighty toighty about it to them. It very well might be full blown sarcastic. Or they might just be mad about you rubbing it in their face.
Its a bit more than that though. Plus like your remark about them costing less than what other people drive. Yes, if you ignore the year. Its much easier to justify the purchase of a newer vehicle which is intended as your primary vehicle for several years (i.e. their level of vehicles of the same year would be quite a lot cheaper), whereas buying a higher end older vehicle, is seen as buying it for the flash still because generally the aspects that made it stand out when it was new, still make it stand out, until it basically flips into being a classic, which will carry the same appeal still, just that its old enough that you're likely foregoing a lot of benefits of newer vehicles for it. If you have the ability to afford a Viper, you already have another vehicle too, so that's part of it as well.
Also, holy shit at you letting other people (I'm assuming not full on randos though?) drive your Viper. Granted they'd need to be able to drive manual so that'll mean they have at least some driving chops and appreciation for driving these days.