Nearly all tools used professionally now are harder than hard Ti alloys. HSS has been niche for decades now.

> and titanium is prone to catching fire during machining (so the work piece usually needs to be submerged during)

Using spray or mist coolant is common in machining anyway for hard materials. Also titanium fires can't be put out with water. That said Ti is not magnesium and does not burn readily: you have to be both unlucky and incompetent.