They didn't buy Rimac, they bought a stake. It used to be 24%, not sure if it's bigger now https://www.caranddriver.com/news/a36920070/bugatti-rimac-po...
They have a glorious flowchart on their site. https://web-cdn.rimac-automobili.com/wp-content/uploads/2021...
Asianometry How the Rich Ate South Korea https://youtu.be/hWCcvOE84Ao?t=489
Porsche did this stake here and there thing precisely to gain > 50% of Rimac voting rights.
It's simple really: Porsche controls Rimac.
Then there's the whole "VW took control of Porsche after the short squeeze made by Porsche to try to acquire VW failed" (it failed due to the sudden crash during the 2008 banking crisis IIRC). And now Porsche is apparently spinning out of VW and shall be independent again.