While money is used to by goods and services, it isn't those goods and services. It's essentially a measure of resource allocation. More money means you get more resources.

People don't go hungry due to lack of money, they go hungry due to lack of food. In an area undergoing famine, you can give people money and they'll buy food. This means people who were eating before are now going hungry. If you keep giving out money, the price of food starts to rise. Keep going, and eventually it's cheaper to leave the country than it is to buy food.

The systemic causes of hunger are complex. The complexity is sufficient that fixing them would take more money than any billionaire has.
In the US for example, we keep production high and costs low by subsidizing agriculture to the tune of $30-60 billion a year. We give individuals about $115 billion a year in money to buy food. Another $3 billion for emergency food aid. Another $25 billion for lunch for school children. Then there's intangibles, like a side effect of food subsidies being the government owning millions of tons of milk, cheese and produce that it just gives to people. Not cheap, but difficult to quantify exactly.
This all has side effects and weird consequences. Like agricultural subsidies driving down costs of grain for the entire world, making it unprofitable to be a farmer in areas with borderline arable land and causing communities to depend on imports for food, making global food market fluctuations another source of famine risk. There's also some obesity and other health impacts, as well as things like improved academic performance, but those aren't relevant to this.

To actually solve the issue, you need to invest in agricultural development. The US government spends another $200 billion a year on this. Basically, instead of just buying food or paying people to grow it, you need to invest in the tools to do so, and to manage pests and everything. Roads, water, tractors, bulldozers, powerplants, education, and all the things that support those things.

All told, the US government spends about $500 billion a year on this, and it's given us a consistently high ranking in food security indexes, with food being generally affordable and safe, and slightly less available, depending on the economy. All that, and only about 50 million people are in food insecure positions in the country.
This is before we get to the costs of doing foreign food aid.
There are billions of food insecure people on earth, and 700 million hungry.

Elon musk liquidating all his assets at face value couldn't cover the bill for one year in the country that needs the least assistance.

That being said, while they can't solve it they're certainly part of the cause. The systemic failures that have led to hunger are embodied in them. If we decided to not allow billionaires to exist, we'd be making changes to society that would actually allow us to make those expensive and overwhelming changes to solve the problems above.
One person doesn't have the resources to build roads and infrastructure needed to build the infrastructure needed to support modern farming in areas that can only scrape by, teach people the new methods needed, teach the people needed to support those people, and all of that again for getting the food to the people who need it. But if society decided people like that shouldn't exist, the resources spent so that some portion of the resources end up in their pocket would be enough to do that.