Question

Why does the Fed sometimes increase interest rates?

to help more people get loans and become borrowers
to speed up the economy and help it grow quickly
to prevent banks from making profits that are too large
to slow inflation by stopping the economy from growing too fast

Answer 1

To slow inflation by stopping the economy from growing too fast.

Raising the Fed's policy rate makes borrowing more expensive, which reduces consumer spending and business investment, cooling demand and easing upward pressure on prices. (It does the opposite of “help more people get loans” and isn’t primarily about limiting bank profits.)