Gambling is a terrible idea, no matter what currency you use.  Lending to strangers on the Internet is a bad idea.  If you wouldn't do it with dollars, don't do it with bitcoins!  Beware of advice received on bitcointalk.org, as 90% of the participants here seem to act like children.

Day trading is a slightly less bad idea.  The idea is to sell some after it goes up, then buy some after it goes down.  However, you should first examine the past history of Bitcoin and remember that relevant past behavior is the best predictor of future behavior.  Bitcoin has historically been subject to occasional major rises, followed by fast crashes.  Day traders often sell near the bottom and miss most of the major rises, and they sometimes buy as it starts crashing, thinking it's probably going to resume the rapid climb.  For that reason, the boring strategy of "buy and hold" usually yields better results than day trading.

Also, day trading requires you to keep balances at exchanges, which exposes you to the risk of theft.  By contrast, with buy and hold, you can keep your coins in cold storage and be much safer.  Investigate cold storage options (like TREZOR), and store your coins securely.

I recommend a combination of "buy and hold" for long-term appreciation, and "spend and replenish" to support the merchants who are already accepting bitcoins and encourage others to do so.

$50 worth is a tiny investment.  I suggest investing 1-5% of your net worth in bitcoins.  That's a small enough investment that you don't suffer much if it fails, but enough to make you much richer if it really takes off.  Think about how rich you want to be,  and imagine how many bitcoins you would need to own to be that rich if the price went to, say, $10,000 each.

However, if your net worth is close to zero, then consider buying $20 or $50 worth every week, whatever you can afford, until you reach your investment goal.

The difference between rich people and poor people is that rich people tend to hang on their money, while poor people fritter it away.  Which do you want to be?