New companies doing IPO every month?

I don’t know if anyone else likes to keep track of which company is doing IPO or not but I closely follow this and every month there is new list of companies and search about them what they do. Most of them we have never heard of. Some are 10 years old and some are less than 5 years older. Curious to know what do you guys think about this? I see people try to find startups and companies to join them pre-IPO and make $$$ but I don’t know how companies like these come out of nowhere and go public.