(After getting 4 downvotes and a comment, I complied by removing the greater part of this answer, because it was considered polemic. Sorry for having been ignorant about the purpose of this list as Q&A site.)
A fork of a blockchain can be compared to splitting the shares of a company, e.g. by increasing the total no. of shares from 100 to 200.
The value of the company stays the same, but instead of 1 share, you now have 2, but they still only represent 1% of the value of the company.
The value of a company and its shares is determined at the stock exchange by monitoring at what price the shares are traded. Initially the 2 new shares will have about the same value as 1 old share. But that changes, depending on how the future development of the company is anticipated.
After the fork the prices of BTC, which has kept the legacy name, and BCH are determined separately on the exchanges.
I don't think that this process can be called "creating money from nothing". Additonal tokens have been created and given value by people who are buying it for a reason.
When a government or central bank "prints" money it kind of taxes the people by diluting the value of the currency.
Crypto miners get coins as a reward to process transactions and maintaining the systemic process. The blockchain protocol is designed to release only relatively small amounts of new coins on a regular basis to not cause "inflation". Still the holders of coins are "taxed" that way, but it is a fair price to pay for being able to use a currency without "strings attached".
Money from thin air ;) More forks might come. As long as somebody believes in it that there is a value in there you can create more forks and more money - what a wonderful world, isn't it? – KOld – 2017-08-19T20:45:18.980
1Anyone can create a fork - I could make one tomorrow if I wanted. What will happen is almost certainly this: nobody will be interested in obtaining my forked coins, so they will have zero value and the value of BTC will remain unchanged. Bitcoin Cash filled a specific need that the market perceived, but if my fork doesn't do the same, it won't have any effect. – Nate Eldredge – 2017-08-23T04:12:47.073