Why do you think Bitcoin is a scam?
Bitcoin is a digital currency, with an awesome technology which finally solved the double-spend problem. It has many interesting features of money, similar to gold: scarcity, valuable, store of value... and sometimes better than gold: liquidity, easily transportable, easy to divide in smaller units... It's fast (10 minutes) and reasonably cheap to transfer, and you don't need a bank or middlemen.
Now you can argue if one bitcoin should be valued $0.01 or $1 million, but the price is only what people is willing to pay for it. And the more people who want to buy it, the higher price will go.
The same house has a different price if it is in the middle of nowhere town or in a big city like Manhattan / Paris / etc. Same house - but different value. One painting of random unknown painter is worth $0 and one painting by Picasso or Rembrand is millions $. Why? Because they are scarce (a small quantity) and many people want them so the price raises.
Some people may think Bitcoin is a scam because it is volatile and change over time. But... food prices change, dollar price changes, gas price changes, house prices change, stocks prices change, gold-silver price change... With one difference: fiat (dollar) is inflationary and Bitcoin is deflationary.
Wanna know what is a scam? Fiat money and (private) bankers printing money non-stop, devaluating currencies. Also Fractional Reserve banking. Google that if you don't know what it is.
"It is well enough that people of the nation do not understand our banking and monetary system, for if they did, I believe there would be a revolution before tomorrow morning" ~ Henry Ford
Duke7 is pointing out a very important issue you need to understand if you want to know if Bitcoin is a scam. Scam is a very widely used phrase and many things in daily life are scams however since they are accepted by society and are not obviously they are not called scams.
The biggest one of all is our monetary system. If you are really willing to invest quite some time to understand how money is created and how powerful it is in shaping society regarding dependency and control, you will understand why the idea and the technology of Bitcoin has a radical potential. Maybe you should try to learn more about money first and then try to understand Blockchain technology and the possibility how it can transform the way we use money nowadays.
And yes Bitcoin works in my opinion similar to pyramid-scheme, however as already mentioned by duke7 there are many similar pyramid schemes types in which we believe and participate in daily life. So far this type of system is stable in long term it is widely accepted, there is no problem or scam. However always understand that a nothing on earth can grow endless (except the stupidity of us humans), so everything has to die/shrink/crash/go down at some point.
And keep in mind, if you can make a lot of money in a short period of time, there is mostly a high risk involved or it is a kind of scam.