Although it may sound strange coming from a professional investment advisor, the answer to the second question is certainly yes. However, it probably is not easy to do it yourself, and even if you can, you may not want to.
Why isn't it easy? First you have to discover what you can do and what works for you. What works for me or your friend who is a whiz at trading stocks may not (probably won't) work for you. People are different. They have different skills, temperaments, analytical capabilities, and the like. Some are very visual and like to extract information from a well constructed chart. Others prefer to "crunch numbers" and develop formulas to guide them, which is my preferred approach. It usually takes years of investment experience including many blind alleys for an investor to discover what works for himself or herself.
Once that knowledge is obtained, applying it usually takes a substantial amount of time. Very few people can be successful investors spending just fifteen minutes or an hour a week. Don't believe anyone who tries to sell you something making that claim. More importantly, once you know what you should do, three things are still required: discipline, discipline, and more discipline. That is, you must be able to execute your methods unemotionally. Part of the learning process is determining what you are capable of doing and what will cause your fears, worries, and possibly greed to get in your way so that you can eliminate or work around those causes.
Many successful investors enjoy the time they spend working on the markets. It is a nice hobby that may become a primary avocation after retirement. Those people should certainly do it themselves. However, not everybody wants to even if they are capable. Several of my clients have told me they have been successful investors (some professionally), but now that they are retired, they would rather play golf, travel, or partake of another pleasurable pastime rather than watch the markets.
In short, the primary reasons for using an investment advisor are: