This is true, and those voters main concern in presidential elections is the economy. According to NBC’s exit polling:

Nearly half — 45% — of all voters said they were worse off financially than they were four years ago. That was a higher level of dissatisfaction than what registered in exit polls in any recent election going back to 2008, when the election took place amid the financial crisis that propelled Barack Obama to victory.

Though the economy is growing […] 2 in 3 voters rated the U.S. economy poorly, a level higher than in 2020, when the country struggled to get in gear during the Covid pandemic.

[…] About three-quarters of voters nationwide said they felt negatively about the way things are going in the country, including 29% who said they were downright angry.

Meanwhile only 4% of voters cited foreign policy (which covers the Gaza genocide and Ukraine’s defense – immigration was broken out into a separate category) as their main concern. Even if Harris flipped the big red “stop the genocide” button and brought those single issue voters out of hiding, there’s no way they could outnumber the voters who were pissed about the economy.

Frankly, if she was going to have a real chance, she needed to throw Biden under the bus – and it still might not have made a difference.