When I went out and raised the first time, there was a company that had raised just before us. I didn't know the company, but apparently they pushed potential investors very hard. They had a mentality that you were in or out, which turned a lot of investors off, even the ones that ultimately invested. Regardless, they were in high demand and closed their round quickly. When we raised, I found myself having to explain that we were different, that we were looking for investors that would be long term partners.
There's a moment in time when your company may be in demand. For whatever reason, a lot of investors want to invest in your company. Sometimes I hear about founders treating potential investors too harshly.
Being a 'hot' company is transient, yet your presence in the valley is long term. How you behave as a founder during your fundraising process will dictate how you'll be treated as a founder in the future. You have years ahead of you where you'll be in a building phase, where you may need your investors' help. You may also go out and raise again in your career as a founder, whether on follow on rounds or with a new company. Besides, closing a round on the terms you like isn't incompatible with observing etiquette and treating your investors well.
The only founders that can afford to not treat their investors well are the ones that are doing so well, so consistently, that they won't need help and will be in high demand regardless. There are a very few number of founders that would fall under that category and many of them didn't know in advance that they would be that type of founder. Even then, it's not worth it. Some of our investors have become great friends and have become a tremendous source of advice. I'd rather live in that world and I imagine that if most founders gave it some thought, they would too.