For a new web app project, did you make a scalabe implementation with kubernetes before the launch?

If I develop a new web application, I know that my server can still up and running at launch. But, if the project is a Big success, the server certainly will crash quickly. In this case, it can create a very Bad buzz. The solution should be a scalabe architecture with kubernetes. This is a very expensive solution. Is it better to wait or to anticipate this risk by increasing the budget and development time?