While I understand and have also myself been guilty of this, I have come to believe that this attitude is selfish and irresponsible.

The experience which gave me perspective was on a project at my previous job. I worked together with another highly passionate engineer and we made amazing progress over the course of a very short time.

The day before the demonstration of our results to our bosses, meant to serve as evaluation and retrospective for this project, we had reached all goals and the simulation was really robust and stable. However, when I came to work on the day itself, I found my colleague sitting at his desk, looking very tired. He'd been working through the night to get all the extra bells and whistles implemented. The demonstration was a disaster. Nothing worked, everything crashed. A lot of people were upset.

Are you missing a /s?

Since this sounds very familiar I would venture that he's being serious.

I feel this is an extremely selfish attitude, as generally it's not just the one who pushed into production who has to do extra work on the weekend, and usually they are not willing to do extra work because someone's ego couldn't wait 2 more days.