You want your cake and eat it too??
In order to reach your goal, (first, you need an organized goal

) you need to have all of the knowledge that is there for the type of guns you want.
Anybody with 2 mil to spend can go out and do this unorganized. The rest of us must be educated and methodical in our quest.
If you get excited or buy on impulse, well, your gonna lose. Its OK to get excited but you better have the knowledge to back it up.
I buy every gun with the reasoning, "What can I sell this gun for "any day of the week--easily". This way if you don't like it, you can sell it and get your money back---easily

Its called business at the "below wholesale level" so in reality, your a business man at a peon level who operates a few times a year--this way you don't break any laws on dealing in firearms. The ATF told me they don't have a problem with citizens selling a half dozen guns a year. Its a different story if you are retiring and liquidate your guns all at once.
The more knowledgable you are, the less likely you will buy junk or a "problem gun".
Parlay, parlay, parlay. You can't do it in a short period of time. Simplicity at it's finest. Study the hot items, buy low--shoot it--have fun--sell high. Always keep a reserve of cash to buy a gun when you least expect to find that particular gun. Remember, your educated now--so buy low--enjoy--keep it a few years or decades---then sell high and buy three with what you paid for one.
For most individuals, the above does not pertain to "utility guns" or guns you use as tools. Most hunters and shooters buy a few and that keeps 'em happy for the rest of their lives. Me? I won't hunt unless I have a hundred year old+ rifle with a tang sight that calibered in a dash numbered caliber.
The
plan You gotta have one

------------Sixgun