As a founder of a new company and the son of a lawyer lawsuits are certainly something I think about. It seems all companies that become well known eventually face lawsuits. While it sucks and you never want to face one, many know it is a cost of doing business. You also find people who want to attack a company seeing a big dollar sign in front of them. Plus lawyers might earn hundreds of millions or dare I say billions if they win a case from a company like Facebook or Google.
...but those millions may take years to win. Every lawsuit has an opportunity cost. Yes if you get to a certain level that is the cost of doing business, but if you are just out of the gate and have X dollars and Y hours in the day that may be a poor investment. Also there's a difference between a disruptive cost in upsetting an old industry (say a YouTube or Napster) vs. fighting a single companies' walled garden. At the end of the day building a company on top of another companies walled garden is a high risk to begin with, so it could be better to just move on.