Note this is my opinion. This has been discussed in the past -- where I have cited examples example of issues faced by countries and the actions taken by them
including Hungary banning his foundation.
However, to be clear, the reason the Open Society Foundation (OSF) has been active in Hungary is two-fold, Hungary is Soros's native country, he founded an important University there which Orban has tried to shut down, and the OSF has sponsored political groups hostile to the authoritarian Orban. I recall Soros mentioning at Davos that the University may be forced to relocate. Orban, like Trump, like Erdogon, like Bolsonaro and like Putin, is an authoritarian leader attempting to consolidate power in himself. These leaders all represent a danger to the survival of democracy. Of course Orban will do what he can to shut down the Open Society Foundation's activities in Hungary. It is decidedly not the OSF, however, that is a danger to democracy, but quite the other way around.
There is so much disinformation re George Soros that it is understandable that many have an incorrect picture of his politics and interests. This disinformation is wide spread on the internet. It originates mainly from countries that have authoritarian leaders hostile to democracies, and then it is parroted ad infinitum.
In Putin's Russia, one of the countries extremely hostile to Soros's OSF, there are elections in which the people vote, but I don't believe anyone outside of the authoritarian countries would characterize Russia as a democracy. In true democracies, the opposition candidate is not routinely jailed or murdered. In the United States, for example, the outgoing President has been calling for the locking up of his political opponent from before his election up to, and including, the present time. He is also interfering with the smooth transition of power to the newly elected President and insisting the election was "rigged". Actions typical of authoritarians.