I have a question about this:
How much money can you make on running a Lightning Network node?
Unless you have a lot of coins, your earnings won't be enough to cover both hardware and maintenance costs.
Why should you have a lot of coins deposited in your LN node? Aren't the users supposed to deposit and be responsible for their channel's capacity?
I'm not sure if the previous replies already made it clear enough, but how I like to put it:
Sure, other users can open channels towards you, but then you can only receive and not send anything. They are thus only able to send funds to you and not use you as an intermediary node to send funds to another of your peers.
Your topology would look like this, with 4 connections for example:
A 1BTC ──────────┐
v 0BTC
B 1BTC ──> 0BTC BlackHatCoiner 0BTC <──── 1BTC C
^ 0BTC
D 1BTC ──────────┘
A can't send to C, unless C has e.g. donated you some funds or bought something from you, so that the channels look like:
A 1BTC ──────────┐
v 0BTC
B 1BTC ──> 0BTC BlackHatCoiner 0.5BTC <────> 0.5BTC C
^ 0BTC
D 1BTC ──────────┘
In this case, you'll be indeed able to forward a payment from A to C of up to 0.5BTC, because your C-channel allows it.
In conclusion, I think it's now easy to see how it's best for routing if you have many, large, and balanced (similar balances on both sides) channels.
The ability to send out money (to forward payments) is called
outbound liquidity. To get it, you need to lock up own funds in channels (because the one who opens a channel of course then has the balance on their side of the channel).
There's a way that allows you to be guaranteed to get as much inbound as outbound liquidity (otherwise if you're the only one opening channels, sure, you can send, but you can't receive anything), which is something like a
triangle swap or
pentagon swap (
https://lightningnetwork.plus/), or you can buy inbound liquidity. But for outbound, you need to lock up own funds. You need both