That's not correct. I've worked from start-ups to semiconductor giants. Always the first option to develop everything in house, if you can find the talent. This is pretty much industry standard.
Pretty much most of them. They might buy a small IP or two here and there, but for the rest everyone develops their design mostly in house. It's not 100s of millions, that's a ridiculous amount of money unless you are designing like a huge CPU or TPU or so. We design (can't give company name) quite large chips with complex analog and digital in 7nm and 5nm as a start-up and our seed funding was less than 20 million. This is kind of bare minimum funding for a semi start-up anyhow.