[fighterpilot]

That's not smart by Toyota (unless they own a very small stake), is it? Mazda competing with Toyota is indeed bad for Toyota but it's also bad for all the other auto manufacturers too. The benefit of that competition goes exclusively to Toyota (among other shareholders) but the cost is shared among all automakers roughly in proportion to their EV market share.

[InitialBP]

Mazda has been focused on continuing to improve internal combustion engines over the past couple of decades. Specifically, the "Skyactiv" technology they developed was built to help improve efficiency and emissions of modern ICE engines. It's likely Toyota wanted to have some group/company (like Mazda) continue working on improving ICE engines while also investing in EVs.

I think ICE vehicles will continue to have a market, especially in very remote areas of the world where power grids are non-existent or not very reliable.