Every home will need at least some electrical work in its lifetime. Hiring a residential electrician can be an investment in making sure the job will be well-done. You might wonder if you need to bring in a home electrician, though, so let's consider the times when it will probably be wise to pay a professional.
If your confidence level doesn't match the project, stop and call an electrician. No matter how easy a random internet article or YouTube video says the job might be, that is beside the point. Even something most DIYers consider simple, such as replacing an electrical outlet, can be dangerous if you're not comfortable with the work.
You shouldn't touch a problem if you're not confident that you can find the electrical box, turn off the appropriate breakers, and handle the task without being electrocuted. If you have even a smidge of doubt, the smart move is to contact a residential electrician.
Some jobs require a licensed professional. For example, virtually anything that involves the utility company's tie-in to your home falls into this category. It is wise to think of the electrical box as a dividing line. Most likely, you can legally touch anything that's on your side of the box, even if it is dangerous. Everything on the other side of the box, including the lines inside the box from the electrical company, is the domain of a licensed electrician. When in doubt, assume the worst and ask for a professional's help.
There are also jobs that may carry heightened liability. If you're running an underground electrical line to your garage, for example, there is a risk that you could accidentally electrify part of the yard. A passerby could hit that patch and suffer injuries. You would be liable.
A residential electrician will have insurance — their work is covered. Let the professional accept the potential liability for the quality of their work.
Some electrical systems can be quite complex. If you want to install a generator or backup battery for the house, for example, the system has to do several things. It has to detect an outage, flip the power over to the backup, detect a return of main power, and finally return the system to normal function. That can be complex, especially if it involves multiple rooms or buildings.
How you wire an electrical system can affect a home's efficiency. The box usually runs on two separate rails, and it's inefficient and expensive to have an unbalanced load. A home electrician can configure the system to maximize efficiency.