There could be several reasons why your friend says he's busy but appears to be doing nothing:
Privacy and personal time: Your friend might need some time alone to relax, unwind, or pursue activities that they consider personal or private. They may not want to disclose all the details of how they spend their free time.
Avoiding social engagements: Sometimes people use the excuse of being busy to avoid social situations they may not feel comfortable with or do not wish to attend.
Feeling overwhelmed or stressed: Your friend might be facing personal or emotional challenges that they don't feel comfortable sharing openly. Claiming to be busy can be a way of avoiding discussing their feelings.
Fear of judgment: They might worry about how others perceive them or fear being judged for how they choose to spend their time. Saying they are busy could be a way to avoid scrutiny.
Lack of interest: It's possible that your friend is not interested in the activities or events you are suggesting, so they use the "busy" excuse instead of outright declining.
Poor time management: Some people struggle with time management, and as a result, they may feel like they are busy all the time even though they are not accomplishing much.
It's important to approach this situation with understanding and empathy. Everyone has their reasons for the way they behave or respond, and it's crucial to respect their boundaries and personal choices. If you feel comfortable, you could try having an open and non-judgmental conversation with your friend to express your feelings and seek clarity. However, remember that they may not be obliged to disclose everything about their personal life, and it's essential to respect their privacy.