Example 1, Dropbox: Google & Amazon seem like companies ideally positioned to destroy Dropbox. They excel at making network infrastructure at scale, they both have competing products and massive existing customer basis. Yet Dropbox has managed to compete and win on user experience.
Example 2, Netflix: Both google & amazon have tons of money and massive amounts of users to cross promote a premium video service to yet neither YouTube nor Amazon seem to have figured out how to produce consistently good original content to the same degree that Netflix has. Netflix should be dead by now yet it’s doing very well. YouTube/Amazon also have much poorer interfaces than Netflix.
I could go on. My point is that plenty of companies successfully compete with both Google & Amazon.