What do you think is the reason for the decline of Saudi football?

‌In the 90s, Saudi Arabia was the strongest in Asia
Reached the Round of 16 in the '94 World Cup and won the '96 Asian Cup
There was even a time when Korea couldn't beat Saudi Arabia for 19 years..
Even during the '06 World Cup qualifiers
They lost both home and away matches to Saudi Arabia
It seems they have been on a downward trend since the 2010s;