QQQ, like most ETFs, isn't a derivative. You get a share that represents a basket of all of the NASDAQ-100 companies. This tracks the price of the components through creation/redemption mechanism. Authorized participants are able to create QQQ by sending a share of the constituent companies to the trust, and they're able to redeem QQQ for the shares in the trust. In this way participants are able to arbitrage the spread between QQQ and the components and keep the price tracking extremely, extremely closely. It also pays a 0.61% dividend because when the component in the trust pay a dividend it's distributed to QQQ shareholders - the ones who actually own the shares of the companies in the trust.

I would argue index investing is far less gambling than stock picking because you're betting on the overall direction of a market segment, in this case tech, as opposed to a specific tech stock. Stock investing, in aggregate, can be viewed as a positive-sum game - the value of your holdings tends to appreciate through the contributions of non-investor participants (company customers buying products -> increase in intrinsic value of the company).

VIX on the other hand is a very exotic product, and it's not an investment - it's a hedge, if you can call it that. VIX is a mean-reverting index that spikes up when volatility goes up and drops back down over time, the notional value of which is based on the premium of calls and puts on the S&P 500 over the coming 30 days. It's the derivative of a derivative - a 2nd derivative, if you will. Note that, importantly, you cannot buy a "VIX," there's no such thing. You can buy cash-settled VIX futures where people speculate on the index value on a certain date, and you can buy cash-settled European-style calls or puts (i.e. they cannot be exercised except at expiration, vs American options which can be exercised any time on or before expiration). You can also buy ETFs like VXX and UVXY that use futures and cash positions to attempt to track the index.

QQQ and VIX are very different things.

[edit] When I say VIX futures aren't an investment, check this out lol. Set the graph in [1] to Max duration. Since 2018 it's lost 96.5% of its value. Heck it's lost just shy of 50% of its value since January 1st. They just continuously reverse-split so the numbers aren't silly.

[1] https://finance.yahoo.com/quote/VXX?p=VXX&.tsrc=fin-srch