The saying there’s no honour amongst thieves also applies to invading Assyrians. Hezekiah must have been devastated when the King of Assyria took the money, then invaded anyway. It was a last ditch effort, and the Assyrians knew it.
2 Kings 18:13-17 In the fourteenth year of King Hezekiah’s reign, King Sennacherib of Assyria came to attack the fortified towns of Judah and conquered them. 14 King Hezekiah sent this message to the king of Assyria at Lachish: ‘I have done wrong. I will pay whatever tribute money you demand if you will only withdraw.’
The king of Assyria then demanded a settlement of more than eleven tons of silver and one ton of gold. To gather this amount, King Hezekiah used all the silver stored in the Temple of the Lord and in the palace treasury. Hezekiah even stripped the gold from the doors of the Lord’s Temple and from the doorposts he had overlaid with gold, and he gave it all to the Assyrian king.
Nevertheless, the king of Assyria sent his commander in chief, his field commander, and his chief of staff from Lachish with a huge army to confront King Hezekiah in Jerusalem.
The money was later noted in Sennacherib’s own records as the reason the invasion ultimately failed.