easiest way to build or gain wealth, I guess maybe not the easiest but the most sure way of it. That is to start a business.
Good economy or bad, you can start a business that can make good money. Stock market high? Real estate market high? Start a business.
In my opinion, working for others is by far the hardest way to get wealthy. That means you are trying to save money to invest in something else, so yes timing and luck will be needed to become wealthy.
However creating your own business means you can create your own source of wealth not directly tied to anything else. Will luck still play a lart? Yes, but in my opinion times of good luck and bad much are much more manageable.