It's the other way around: I took a look how Lightning works, and understood that, unless you open and close channels constantly, you don't interact with Bitcoi

It's the other way around: I took a look how Lightning works, and understood that, unless you open and close channels constantly, you don't interact with Bitcoin at all. Repeating soundbites you've just heard without understanding the system would be saying "LN fixes Bitcoin's speed problem". While a channel is still open, transactions happening on the channel aren't in any way protected by Bitcoin's guarantees (they get LN's guarantees, which are different). And those are the only transactions that have any speed boost.