For years, many people understood airsoft as a constant succession of fast engagements, instant respawns, and games where the important thing was simply shooting more than the other side. Milsim proposes something completely different. Here, airsoft stops feeling like a video game and becomes far more focused on management, communication, and endurance. 

And precisely because of that, many people discover in milsim a completely different way of playing. 
In a milsim event, firefights often stop being the most important part. What usually becomes difficult is everything that happens beforehand: moving without being detected, maintaining communication between teams, managing ammunition, water, or batteries, and making decisions after hours of accumulated fatigue. 
Because yes, fatigue completely changes the way people play. 

After several hours walking, sleeping little, and carrying equipment, the initial aggression disappears quickly. People move slower, think more carefully about each movement, and begin to understand why coordination ends up being far more important than running fast while shooting. 
Teamwork also changes completely. In normal games, groups often function in a fairly improvised way. In milsim, constant communication becomes essential. Confirming positions, controlling sectors, or simply transmitting accurate information can matter far more than individual shooting skill. 

Objectives also become much more complex. It is no longer just about eliminating the opposing side. Reconnaissance, extraction, escort, area control, or resource management force players to constantly think about what is truly worth doing and which risks are worth taking. 
And that is where one of the most interesting aspects of milsim appears: it forces players to slow down. 
Many discover for the first time that not shooting can also be a good decision. That avoiding a fight may be more useful than winning it. Or that remaining still and observing for twenty minutes can sometimes be worth more than emptying three magazines around a corner. 

Milsim does not try to turn airsoft into real combat. But it does try to approach sensations that rarely appear in normal games: fatigue, pressure, uncertainty, and absolute dependence on the team. 
And that is precisely where many people realise that airsoft can be much more than simply running and shooting.