As a software engineer/computer scientist your success doesn't depend on any specialization but rather your ability to solve problems, understand users and most importantly your ability to learn and apply new information.
JDBC is a technology used in the Java programming language to interact with databases. It's just one of the myriad of Java technologies you might encounter if you chose to learn Java. However it's not a good candidate for specialization as it's only one tiny part of the puzzle that is a software application.
Income, Stress, Bosses, Worklife, etc... will all depend on the companies you choose to work for. Some types of software development companies are known to have higher burn-out rates and worse working conditions on average (such as games). But your actual situation will vary greatly from company to company as with any other field.
What's most important is just to be interested in software. Write a pet-project or learn a language on your own initiative. You need to constantly excercise your learning muscles and learn how to write programs that help you solve a problem you have right now. As you learn more about programming it'll become easier to grasp difficult concepts. You don't need to study 24/7 but it's important that you enjoy the process of learning new concepts.