I think this :
in the forum there are many users
1. those who are interested only in reading or just out of curiosity or for their own personal purposes, update their Navi and then say hello!
2. who likes to contribute to common knowledge
3. who has an interest only in selling
so the characters of point 3 ... obviously push to buy and advise against the upgrade to free
while I think the correct thing is to give all possible options ... instruct how to update for free and solve the problem in case of problems, then as a last remedy propose payment ... but obviously if you just want the gain then the "safest solution is to pay" .....