The chip manufacturing industry would have spent their own money building fabs based on demand projections. Government money (my tax money) does not need to interfere and give free money to them. This is my point.
You are right that those semi companies do not need the government investments to build fabs. However, those fabs materialize overseas, depending on overseas supply chains. The EU and US regions want to build out more of the supply chain domestically, for strategic reasons. Those governments could simply legislate to impose heavy restrictions, but that hurts the competitiveness of the companies involved. And so, they combine that stick with a carrot, which is the government investments. You can already see increased restrictions on the semi supply chain in China, timed right after the CHIPS act passed.