You should be dedicated to your company, but you should never get attached.
Too many founders are on an emotional rollercoaster with their companies--when you close a big deal you're riding a huge high, and when a key customer cancels, you can't get out of bed. That's happening because you're tied up in and trying to control everything, taking everything personally.
This is one of the most frequent failure patterns in business: trying to do too much and not doing well at any single thing. A product with a breadth of features, but no depth on a single use case. A CEO running product, engineering, and design--but not running the business. Outsiders can see the mistakes you're making clearly, but you can't see the forest for the trees.