I am very curious about people and sin. I try my best to not sin. Stay away from major sins that are easy to access in western cultur where I live. Many Muslims I have met much older than me have been the worst not only lifestyle with zina and drugs but also violence arrogant and unfair behavior towards everybody. They reach a age where the youth has fade away and now the repent and become religious.

What is the status different between those ppl and those who even in their youth behaved, treated people good, prayed etc. It seems unfair that the other part “enjoyed” this Dunya and used all those “good” years on doing exactly what they want when they wanted and then they repent and come to Jannah, while others “struggle” the whole life to be good human beings and good Muslims. I have heard people being happy about their experience – this saddens me. I have always tried my best to be on the right side. Always feared for punishing and now the people that have sinned all life can just get away with it. Please don’t misunderstand I am just confused. Because I really make effort, and when I watch people laugh at their dirt past and be proud they are righteous now. It saddens me.

Of course living a lifestyle while refraining from sin is much healthier and better for a person. First of all no one knows if their repentance is fully accepted. It is only accepted if a person is sincere.
Second, living a sinful lifestyle becomes addictive. It becomes very hard to get out of it and change your life. This is like someone doing drugs which damage the body, then going into rehab. It is obviously must healthier to not go drugs from the beginning.

The third point is that no one knows when they will die. Perhaps they die while they are sinning and this will be their end. So it is much better to refrain from sin because sins destroy our life and afterlife.