It's not making fun of the fact he's balding, everyone knows how powerless we are to that, but his stupid reaction to it. How could anyone think a razor sharp toppik line wouldn't be detectable? It looks like magic marker.
Because of tools like him, people who were never aware of this product now know that balding guys use it, and I may not like it myself but a lot of toppik users don't want their secret detected. Toppik is detectable only when someone's a complete nutcase and makes it obvious, or if people are aware that others use Toppik, then they are more likely to notice. For most people using it reasonably, it's not noticeable to 90% of other people, only the baldite community will recognise the use of it as we're aware.
Also, now he may as well get a hair transplant. I'd say he has the money, as most popular youtubers do, and cut his losses. The only reason I don't go out and get a hair transplant tomorrow is because I'm scared of being mocked for vanity, he's already past that stage now (and also seems a bit gay/metrosexual so they get away with it regardless) so what's holding him back exactly?
Just get a hair transplant, I wish I had that freedom, instead of having to keep up this image of being a secure manly man with my balding head.
