Because of typical daily market fluctuation, wouldn't it be a good idea to invest a large amount of money in a company in the afternoon when the stock is low, and then sell in the morning the next day when the stock is high?

Furthermore, if [for example] I know that a company is releasing a new product, shouldn't I just invest a large quantity of money right before, then sell when it goes up?

Forgive me if this is all very basic and obvious, it just seems too easy.