I did a long time ago. I was a very mediocore software engineer but naturally good at story telling especially when it came to explaining complex things. I first became a systems engineer (SE).

I worked at a large company accompanying sales people. I got the technical close (made our solution work for their problem) and the account executive got the financial close (got them through terms and conditions and signature). I eventually got the opportunity to switch to AE (switched because the comp was 2-3X of an SE). How hard can it be? There was a steep learning curve. My perception as an engineer was that once I got technical close, the deal was done. In most of the sales presentations I did 80% of the talking/convincing. But it turns out this wasn't the case at all. I later learned that the AE would cold call the champion after the preso. That's when they made the sale.

They AE motivates the champion to get the deal through the bureaucracy of their company AS WELL AS your own company. This has nothing to do with rational logic you learn in engineering, it's all soft social communication skills.

The best way I can summarize it is an SE/ENG is paid to know the answers. The AE is paid to ask the right (tough) questions at the right time.