People with less grip just have to be more careful. My daily drive weighs 700kg and has 235 wide tyres - everything else I drive has no grip in comparison, and my level of caution increases to cope.
That said - grippy tyres for a mk1 or mk2 MX5 are pretty cheap, so you’ve have to do tens of thousands of miles a year for tyre replacement costs to be an issue.
Original Yokohamas - 14,500
Goodyear Eagle F1 - 27,500 {grippy when new. Still legal maybe 2mm when changed but didn’t realise quite how bad the lack of grip had become till put new tyres on)
Goodyear NCT5 - 29,000
Goodyear Excellence - 26,500 to 34,000 {changed as pairs rather than set. Changed second pair with 3mm left)
Mk2.5
If you want an excellent all round tyre then Michelin Exalto2 won’t be beaten for longevity, dry/wet grip, noise, quality. You do pay for it though. I buy them for around 65 each. I don’t feel the Toyo grips anywhere near as good in the wet. I’m currently buying Toyo as I’m sliding it everywhere.
Michelin lasted 12-15k mile ( thrapping and occasional donut or three )
Toyo t1r- 5k with same as above
Bridgestone er300- 18k with normal spirited driving. Shite lateral wet grip and poor ride comfort