A lot of Uglies (hehe) take sides on just about any topic. The worst happens when it is about professional gear and processing.
I might be mistaken but i believe we should define the terms precisely so everyone would be looking at the same apple.

A. A professional is someone who earns their living from their activity.
It does not always mean they are experts in their careers, just that they are earning out of it.
An attitude or way that directly improves the activity

B. An amateur does things for the love of doing it. They do not get paid and although it also means incompetent, many amateurs are far better and knowledgeable than some professionals.

C. Hobbyist are those who endure serious leisure pursuit having no significant professional counterpart and being too poorly remunerated to constitute a livelihood. Hobbies are usually, but not always, practiced primarily for interest and enjoyment, rather than financial reward.


Well if we look at the above meanings, then:
1. There is no such thing as a hobby photographer as photography is a career choice.
2. There is no limit to what can be called a professional camera. Professional is the person and whatever that person is using is a professional tool. Is there an entry level hammer? or an entry level phone?
3. If we look at boxers, we can also see that being a professional does not always mean you get better the longer you are into it.
4. If someone get paid, he is no longer an amateur but either good or bad professional
5. Professional only means there is money involved. An amateur racer, basketball player and so on, do not get a power up just because he signs a contract.
6. Professional only means there is money involved. The more he can rely on it as a primary means of living then the more professional he gets.
7. A Celphone is a professional camera when used by Pollock.
8. A Nikon F is an amature camera
9. The Canon 7D is expensive
10. Just like fish and meat, some like it raw, some like it scooc
11. Neutral grey will join the nearest software.
12. If you are reading this, perhaps you now understand the absurdity of some of the things being discussed.

We are all in the same boat, let us learn together instead of butting heads and rowing our own way...

Hedgehogs in all their prickly glory can sit side by side together in the same den because they are family.

2. There is no limit to what can be called a professional camera. Professional is the person and whatever that person is using is a professional tool. Is there an entry level hammer? or an entry level phone?

I don't agree with item 2. Was this really a written meaning in a book? There are some tools that could be considered amateur and professional. For example, I use precision measuring instruments in a machine shop. Calipers are used extensively for making measurements. The least accurate are made of plastic and would not be considered by people making a living as a machinist. Only a hobbyist would consider those. The best ones are stainless steel and even have carbide jaws for wear resistance. The best ones even have digital readouts.