ETF

In simple language, ETFs(Exchange Traded Funds) are collections of bonds, stocks, and other assets. Stock exchanges trade ETFs, which are investment funds. When you buy an ETF, you are buying shares of the entire collection.
It's very affordable; you can easily buy and sell the ETFs at market price. It gives you broad market exposure. 
So it's always beneficial to invest in ETFs, as you can easily diversify your portfolio, which ultimately reduces the risk factor for long-term investment.

Ultimately, its your choice where to invest. But I suggest:

Invest in stocks when you want high returns with the high-risk factor. FDs are the safe options with assured returns, with a low risk factor. ETFs offer you a diversified portfolio with not too much risk and good returns.

Economic analysts predict to increase the economic growth of the USA, the interest rate should be decreased. Undoubtedly, the US aims to expand its economy in order to boost the country's GDP.
In the case of ETFs, the market is saturated, as it reached the $1.1 trillion mark last year.

SCHD and VYM both give stability, but their growth is slower than other ETFs like QQQ or VIG. If your objective is consistent income, not fast growth, then they perform well. You are therefore lacking nothing; the focus should be on matching your financial growth.

There is no need to switch totally to ETFs. You can keep your stocks and add other ETFs like SPY or SCHD to your portfolio, as they provide more stability and broader exposure to you. My suggestion for you is to just maintain your core stocks and invest in ETFs for better diversification and for steady returns.

Investing in VTI is a good decision because of its broad market exposure. Managing the market is challenging, so start early with small, regular investments can reduce the risks from short-term market ups and downs. Try to balance VTI with safer investment options like Treasury bonds, Blue-chip Dividend Stocks, Treasury bills and others.

Investing needs diversification. Investing in UD Dividend ETF is a beneficial choice. To diversify, you can explore other ETFs like VXUS, IEMG or VWO for global exposure.

For long-term growth, all four ETFs are excellent options. SPY provides exposure to the S&P 500 and a diverse range of large-cap US companies, making it an ideal choice for long-term growth.
VOOG and SCHG focus on growth stocks, which provide possible profits, but more risk is there. 
QQQM primarily favors technology companies. It provides more volatility but also more growth potential.

So if you want long-term growth, then SPY, VOOG, and SCHG can be beneficial options. If you are seeking a more rapid expansion, QQQM is the best option for you.