Welcome to Bitcoin and to the Forum!
The questions you're asking are great ones. However, they're also questions that you can find answers to REALLY easily on this forum or Google. I'd encourage you to do some reading here and then come up with some more specific questions.
I can help get you started with some simple answers.
Why would I invest in bitcoin? All sorts of reasons ranging from pure curiosity to love of new technology to investment diversification. Bitcoin is used as currency to buy things and as a store of value, i.e., a place to house your savings with hopes of value appreciation or hedging against the depreciation of stocks or savings held in fiat currency. One example often used is that of Cyprus. Are you familiar with the country of Cyprus and it's severe monetary crisis from a few years back? It was so bad that the Cyprus government controlled how much money their citizens could take out of their banks. Think about that. That government telling you that you can't access your very own money! How scary is that? Bitcoin offers an alternative. No government (currently) can seize control of your bitcoin, this represents safety and security.
What's the difference between bitcoin and dollars? Bitcoin isn't regulated by any government. It isn't created "out of thin air" as fiat currency is. There will only ever be a finite amount of bitcoin, which controls it's value. Once all bitcoin is mined there will be 21 million in existence, that's it. No one can ever create more (as is done every year with fiat currency). When fiat currency is created by central banks they reduce the value of the existing currency in the market, which results in inflation of prices. This is why the price of every day things (that haven't changed in 50 years, like groceries or utilities) have gone up in price over time. There's a lot of other differences, but it's better for you to read up on them.
Why would I gamble with bitcoin? I don't, but if you want to you can gamble for significantly smaller portions of money (like cents as opposed to dollars or tens of dollars). And you can do it from the convenience of your computer.
Here are a few links for you to explore:
New To Bitcoin Thread:
https://bitcointalk.org/index.php?topic=7269.0 Why use Bitcoin? From Coindesk.com:
http://www.coindesk.com/information/why-use-bitcoin/Feel free to respond with other questions. I think you'll get better response if you educate yourself a bit first and then come back with more specific questions.
Have you bought any bitcoin yet? Do you have a wallet yet? (If you don't, PM me and I'll set you up and give you some bitcoin)
Good luck to you!