I currently work for a medium-large (~500 employees) Italian company as a Linux developer. I work in a team of 8 people, most of them are really awesome and really friendly, the day life is good and so is the comfort that the company offers.
To reach the office I have to drive around 75km per day, on alternating weeks (I share the car with a colleague), so around 750km per month just to go to and from work. My salary is ~15% less than the Italian average for the position I cover.
A couple of days per month I also work for another company, way smaller (around 10 employees) which is 10km away from my place. There I work with a guy that is a consultant for the first company. We work quite well together. The office is often almost empty since more than half of the team work in a different city.
Recently the new company asked me to join them as a full-time developer, with a salary that is almost double my current one.
I don't know exactly what to do and what I should take into account to choose what to do.
I feel guilty leaving my current team knowing the difficulties we are facing right now (mostly because the team is too small for the amount of work).
(Of course I can earn more money and gain more free time in the new job.)
Should I have concern for my previous workplace, when considering a new job?
Some extra info: I've worked at the first company since January 2018 and I'm almost 23 years old.