And only then if they had a sufficient power base that would endorse said claim. Many are the apparent heirs that died without a crown on their head despite hav

And only then if they had a sufficient power base that would endorse said claim. Many are the apparent heirs that died without a crown on their head despite having a legitimate claim to the thrown. You're underestimating how much effort went into maintaining said power and how much effort was required to keep those people supporting the king happy. Surely, a king has many options in how to play these power games and come up ahead but his life hardly consisted of cruising along doing what he pleases like many rich people today.