I strongly disagree with this opinion, even though it is sadly common.

Go speak to an adult with ADHD, listen to them and find out the real pain and anguish experienced by someone with ADHD. Many people desperately want to do well in school, have a career and successful relationships but are held back by their disorder. Instead, they experience joblessness, poor human relationships and unfulfilled dreams. People with diagnoses in later life experience genuine grief. The medication and counseling can help a lot, but it can't fix a divorce 10 years ago or getting fired repeatedly. The damage is done.