You are right, lauxanh.

I always think big... The reason I said server is because the monthly cost.
Let's do a small calculation: I buy a decent server for 1,500-2,000 and I collocate it for 70$/month. I think VPS costs arround 40$-70$/month... not sure. If my site grows, there is a chance I need to move to a server and go through the pain of transferring all my data, check the server components, security etc. With my server, I have plenty of time to analyze the traffic and decide to buy another server and set it as worker that will serve the same content, mirrored.
If you have several shared accounts you probably pay like 20$/month for all of them summed. I agree that for some, $2,000 is a lot of money and also the monthly costs of $70 might be high. But on the other side, it is your own server, you do not rent so you save money. Also, you can host your buddies on your machine and split the monthly cost with them... while the machine is yours.
Just a different way to look at the hosting and think that eventually your site will need like 15 servers to handle all traffic.