Tom Bombadil is (probably) the avatar of Arda itself, which makes him far stronger than a Balrog, but not omnipotent. Theoretically if Tom Bombadil had to solo the entirety of Morgoth’s forces in Dagor Dagorath, then he’d probably die, but who knows what would happen to the planet after that ¯\(ツ)/¯
New Theory: Tom Bombadil is a reformed Balrog.
Tom Bombadil is (probably) the avatar of Arda itself, which makes him far stronger than a Balrog, but not omnipotent. Theoretically if Tom Bombadil had to solo the entirety of Morgoth’s forces in Dagor Dagorath, then he’d probably die, but who knows what would happen to the planet after that ¯\(ツ)/¯