Not at all. The judges appointed by the opposition party, protect the laws made by the opposition party, when they were in government. This way the government can not just ignore those laws. So most countries have very long term limits for judges to deal with that. Hence a single government can not just stack the courts. Term limits are used, so no single government just happens to be able to appoint a lot more judges then usual. However even with the term limit being death, a court like the US supreme court has judges appointed by five different presidents for example.
There are big money donors, which are not billionaires. The most common one are unions.