Should I do a Master's degree if I am already employed in the field? I am very torn about whether to take the plunge to do a Master's degree. I graduated a few years ago with  BSc in Maths which I didn't particularly enjoy, only the statistics and programming courses. I then got a job at a big technology company in their R&amp;D department doing research and applications of data science. I thoroughly enjoy the work I do but I am also interested in developing my skills further. I want to gain a deeper understanding of artificial intelligence and am also interested in spatial data science. I am not sure whether I should continue in this role or at a different company and learn on the job or invest some time and money into full-time education. I am also not sure whether in the future with only an undergraduate degree I would be able to progress in my field. 
I am also concerned about age, whether it's wise to go back to university at 25.
First, research if your company has incentive programs for higher education. Many top companies offer partial/full tuition reimbursement to qualifying employees to pursue a masters. If this is the case, use the program to take 1 or two classes a semester. Frankly, a person with a bachelors can usually attain the same titles and salaries as a masters. The biggest difference in salaries/titles/responsibilities are between masters and PhDs. The main difference is that a PhD can be a PI on research grants/studies.
I went back to University when I was 30. Sometimes the market calls for a change in careers. But as I stated before, you may not have to "return". If your company is flexible, you could attain a masters on the side within 3-4 years by doing classes in the evening/weekend/online.