They'll just turn around, provide better service at lower prices, drive spacex out of the market, and raise them again. They have a lot more money to play with (and their infrastructure is much cheaper to maintain).
"They" meaning... every ISP on the planet? At the same time? Starlink will have the ability to offer coverage globally, even in places where existing ISPs have no infrastructure.
Not to mention that that kind of predatory pricing is illegal in many countries.
Not to mention that that kind of predatory pricing is illegal in many countries.