I think a middle ground is probably best. Choose a tech stack that can scale but doesn't slow down programming productivity much. Something like node, python tw

I think a middle ground is probably best. Choose a tech stack that can scale but doesn't slow down programming productivity much. Something like node, python twisted/tornado or Go-lang. Same idea for databases. Using the right stack will usually get you up to a few thousand users without major headaches, after that you'll have to know what you're doing. There are startups that fail to scale to a few thousand users, who are easy enough to find for a free service. It's not a nice problem to have when you're not making money solving it. A little scalability planning ahead helps, gives you more time to work on the product. The general advice on HN is to ignore scalability at first. It's vague advice to a vague question.