Concept #1: Opportunity Cost: Everything has a cost. Everything. At a minimum, it is the foregone time you could have invested into other activities rather than the thing that you've chosen to invest time in. Even if you had unlimited funds, you still have to chose what to do with your time, and that's frighteningly finite. Realize, therefore, that you are always giving up something, and choosing to be weak in one area in return for being strong in another. No one is good at everything. No one has it all.
Concept #2: Labor-elasticity relative to wages/money can be negative, and that's ok. For those not keyed in on economic mumbo-jumbo, that simply means that having more money can result in people choosing to work less. First year economics people (and i'm assuming many young, and HN-types) assume that everyone will do more work for more money. But money is not the point, and unless you're neurotic and insecure (and most people who chase money are), there comes a time when you realise that maybe now that you've got money, you can instead use it on the things that really matter rather than trying to get more of it. And work, on the whole, is not the shit that matters...
Concept 3: Be humble and self-critical. Humble to realise how fallible and pathetically human you are, so that you don't beat yourself or others up too much, and how much luck had to do with any success that comes your way, and how much it has to do with a great deal of suffering that comes the way of others. Self-critical so you can deal with, improve upon and compensate for the flaws you realise you have.
Bonus concept 4: Learn from the things stupid people do so you don't do the things that make them stupid. Their sole purpose in life is to act as a warning to others.