Compare to shares in a real corporation, say AT&T.

There are colossal assets backing the value of the shares:

1. Current profits & dividends.
2. Massive network of equipment and cables.
3. Market share.

How low can AT&T's price go?

So long as it is making profits and paying dividends, its price CANNOT go below the current value of expected dividends discounted for the future.

https://investors.att.com/stock-information/historical-stock-information/historical-common-dividends/att-inc

AT&T has been paying a quarterly dividend of $0.2775 per share for many years (adjusted for stock splits).

https://www.calculator.net/present-value-calculator.html

Over ten years at a quarterly dividend of $0.2775, the Present Value: $4.76

Hence, it is highly likely that (assuming current conditions continue), any rational person would pay $4.76 for a share.

Now, what assets back crypto-currency? NOTHING? What percent return on investment does crypto-currency pay? ZERO. Hence, its present value is exactly ZERO. Any non-zero value is due to PURE SPECULATION.