I do whenever I have some money to spare. I consider it as a cheap investment with a high return in the end. Also, I'm not a paranoid to check out prices too often in a single day, so buying and forgetting is a nice way to do when you invest in bitcoins.
One of my problems is that. It is like a disease and I always look into its price if there is a big change even if I really dont have that big investment. I think those who should always look into its price are those putting a lot of money in bitcoin.
Bitcoin is an long term investment for the majority of us and that is the reason people are putting their money into hoping to make best profits in the future.