Investors are rich people. Like they are very rich and they are also the ones who can make you rich, and if you are lucky you will become rich with the same setup that has been known for years.
Some of the startup founders enjoys taking fun out of life. Who says the startup journey has to be boring? When the office is small, and there is a pressure for the initial profits, this might come handy! If I was in this office, I would love to have free beer!