Not to directly tell you to invest in Bitcoin but some aspects that Bitcoin is way better than altcoins is because

-widely use of Bitcoin by huge service companies
-can survive a bear market - while many altcoins die(value and the market cap goes to zero) during bear season, Bitcoin has proven and is likely to survive another bear market as seen in the past.
-highly unlikely to go zero

The only advantage of altcoin is its value may go up to 10000% unlike Bitcoin where it's starting to stabilize because more and more people are into it. But that would be equal to gamble because you're more likely to get scammed than picking an altcoin that will have that value since you're picking from 1/10000 quality altcoin.