Hi as someone who employs and select developers i agree with a lot almost sayed but think of what are your strengths and where you are or better where your customers are. If you search for big enterprise projects spring boot is ok sql is must and html css as well. if you want to go more to internet related companies (like airbnb, what sup, facebook ) or similar (and not asia) then react is a must node js as well. The libraries tools etc which are used you need to adopt fast. If asia then VUE is a must. but if you like small projects with individuals or like wordpress or similar then you can learn php but i think in 2020 it is wasted time. Same for python in that area. and i also see that we often have problem that developer at least must understand docker docker compose better as it works with kubernetes ,.. just my 5 cents