The state financing parties is pretty valid and is practiced in many countries.

For example in Germany parties get paid around 1 € per vote received in elections.

millions in assets

Rich people and corporations will always be able to use their money to influence politics towards their interests.

Influencing politics works in other ways besides direct donations. The rich can put money into:

• media
• interest groups
• education
• studies
• events
• scholarships
• NGOs

Influencing voters to support your desired policies works well.

Then there’s of course the promise of investments, if policies are changed to your interests. In the simplest case this is a local government changing zoning, building infrastructure, softening environmental or noise regulations in order to for an investor to build a factory. This in turn brings money, employment, and tax revenue to the local government.

Instead of direct donations, a politician can be hired to give a speech somewhere.

Or less directly, hire the politician’s child into a well paying position.

Promising a politician a well paid job for their time outside government is of course also a popular way.

Of course you can regulate all of that in various ways to make it more difficult or at least more transparent.