Why do startups outsource?

It’s not a mystery that most of the startups outsource the development of their products.
However, the question arises. 
Why do not just build an in-house team of developers? It’s more efficient!
Obviously, yes. But not on the MVP or pre-seed stages.

Let me explain why it could be efficient to outsource an MVP development:
1. Cost.
It’s, actually, obvious. The in-house team of developers is too expensive when you don’t have any revenue.
2. Flexibility.
MVP isn’t a ready product, so you may change the concept several times.
Outsourcing allows you to be flexible and you may adjust the technology stack or the cooperation model when it’s necessary
3. High-expertise developers.
Some outsourcing teams have a huge experience of participating in various projects and they work with the latest technologies. This allows them to think “out of the box”. For example, professionals of Edicasoft participated in more than 100 projects in total.
4. Concentration on the goals.
Peter Drucker said “Do what you do best and outsource the rest.”
Development is important, but there are so many other things that should be completed.