There’s a really good video explaining how BGP works https://youtu.be/RT-1DU33xIk?is=i6Vevv2AN_jZ9oHa

The link is now down it appears.

I was briefly a network admin way back in the early 2000s. Core ISPs were playing (often petty) games with BGP routes back then for various reasons (eg forcing sub-optimal routes via AS padding unless downstream ISPs paid up). For awhile it got bad after the Dotcom implosion and networks were trying to up revenue. I've been out of the core BGP game for so long, but it's interesting to see how some things never change.