Competition
Simply put, the more developers, the higher the job competition. Languages with a wider following are also going to have more people vying for available jobs.
GO
Used for websites games web services systems programming
medium barrier to entry
high demand
high pay
medium to find help
Java
Used for websites web games mobile apps desktop apps hardware
medium barrier to entry
high demand
high pay
easy to find help
Javascript
Used for websites web games mobile apps desktop apps
low barrier to entry
high demand
low-high pay
easy to find help
Kotlin
Used for websites web games mobile apps desktop apps
low barrier to entry
high demand
low-high pay
easy to find help
PHP
Used for websites web games mobile apps desktop apps
low barrier to entry
high demand
low-high pay
easy to find help
Python
Used for websites web games mobile apps desktop apps
low barrier to entry
high demand
low-high pay
easy to find help
Swift
Used for mobile apps desktop apps
medium barrier to entry
medium-high demand
medium-high pay
medium to find help