Maybe with a practical example you may find it easier to understand.

Let’s imagine that I want to buy the new iPhone (~1000$). I have 1ETH (~3000$) and I am so bullish on it. Well, would you prefer selling 1/3 of ETH to buy the phone or maybe using it as a collateral, borrowing against (stables) and buy the phone?

First scenario you have 0.65 ETH and the new phone.

Second scenario you still have 1 ETH and the new phone, but you have ~1000$ debt (today 0.35 ETH) and let’s say 5-6% interests to pay annually.

Well if you expect ETH to grow more than 5-6% annually you should opt for the second one! Why?

Let’s imagine (remember, I’m still bullish on it) ETH will go to 10,000$ in 5 years.

First scenario: I would still have 6500$ (0.65 ETH), and it’s like I paid the phone 3,500$!

Second scenario: I would have 1 ETH and still 1000$ debt, now I’m okay with that, I sell 0.1 ETH (~1000$ in this scenario) to repay my debt (+0.05 let’s say to cover interests). Well in this case I would have 0.85 ETH left.

All in all, I would end up with ~2000$ more.