Amazon, Apple and Alphabet have a combined market value of $2.5 trillion. That's enough to buy all 33 oil and gas companies in the S&P 500 energy sector — and still have $1 trillion left to scoop up JPMorgan Chase, Bank of America and Wells Fargo. Of course, tech stocks are booming for good reason: These companies are making gobs of money. And they're disrupting entire industries.