In a word, this parable is about "Industry." Instead of complaining about the tax burden and the economy (problems which are as relevant now as ever), Franklin believes we are obligated to help fix a stagnated economy by adding energy to the market. He feels that by being industrious instead of entitled, the economy could pull itself up by the boot-straps, so to speak. He is advocating for real economic investment amongst the public. If the people want a better economy, he feels they should create it from scratch.
That means that they have to be able to follow one idea to its fruition, and they need to focus their time on ideas that will actually work. This brings us to the problem of wisdom. Because wisdom is different than knowledge, many people in this story operate with technical understanding about the tax system and the economy, but they forgot the value of wisdom. But, they aren't using that knowledge to help themselves in life, so Poor Richard feels their whining and complaining is a sign of their ignorance or their laziness—they either forgot that they can compete for themselves in the market, or they are unwilling to do the hard work of learning how to build a business.
These problems have only grown in scale and complexity, but the parable is still applicable in one's own endeavors, since it is still the case that in order to succeed at anything in life, one has to have the wisdom to understand things both technically and strategically. Having one without the other doesn't work. This is how these ideas all tie back into wealth: The Way to Wealth is the way of wisdom, he feels, because only by wisdom can a person know how to work in an effective, consistent way through time until they succeed, and only by wisdom can a person realize the importance of Abraham's final bit of advice—save money.
