I think both ways work. Focusing on a single product failed for me, focusing on many small bets worked.

Many small business ideas which can be built quickly are really hard to scale beyond a certain point so having many is the only way to build reasonable income. These small bets also need to require low effort to build and support (eg. think b2c with advertising income or a product with little support costs).

Of course if you can scale up a single business, good for you, you can focus all your energies there and provide a great service.