If you are not taking panic attacks seriously, then you don't have panic attacks. True panic attacks are traumatic and highly distressing...you may feel like you can't breathe or you may have a heart attack. True panic attacks are disruptive to your daily life and functioning.
On the other hand, if you are witnessing someone who has panic attacks and do not take it seriously, then you are being highly unsupportive and invalidating. If someone you know has panic attacks and you care about this person, then you need to get this person help. This person needs to see their doctor to make sure there are no medical conditions that are triggering the panic attacks. If the doctor finds no physical medical condition, then the next step is a referral to a psychiatrist and to consider treatment for anxiety.
You can also direct this person to AnxietyBoss.com for self-help on panic attacks and anxiety, and to consider KalmPro for the panic attacks.