I did this as a first employee(software engineer). Crashed out in 4 months. One of my worst mistakes ever. Reasons:
1. It felt like most of the times, I am the only one building the product while the CEO(non-technical) was reading blogs and plotting strategy for a yet non-existent product.
2. The success and failure of the product somehow shifted to me, as I was the only guy actually building the product. Wouldn't have felt bad about it, if I was a co-founder.
3. Since, the other guy is now the boss, he would come up with strategic personal inputs to magically transform the product into a unicorn, without backing it with any arguments. This was the most frustrating thing.
Now, I don't see how anyone can validate being a first employee for a start-up.
"...while the CEO(non-technical) was reading blogs and plotting strategy for a yet non-existent product."
"...he would come up with strategic personal inputs to magically transform the product into a unicorn, without backing it with any arguments."
This is exactly why I will never again join a startup founded by a business guy with no technical background or willingness to learn.
Now, I don't see how anyone can validate being a first employee for a start-up.