Bitcoin is not backed by any physical asset like Gold nor by any fiat currency. It makes me wonder if I should invest/trade in Bitcoin or not?
Gold is not backed by anything either.
Why do people say that things can be backed by gold?
Because Gold is scarce and considered valuable and is useful as a monetary asset.
Bitcoin is scarce and considered valuable and is useful as a monetary asset.
Bitcoin doesn't need backing because it is the type of asset that other things could be backed by. Bitcoin IS the (potential) backer, the way Gold is.
Just as Dollars used to be backed by Gold, Dollars could one day be backed by Bitcoin. Not saying they will, but that'd be the same type of idea as being backed by Gold - backed by a scarce valuable asset that can't easily be manipulated. Why do you think people call Bitcoin "digital gold"? Precisely for this reason. Bitcoin has the special features of Gold (but far improved than Gold) that allows Gold to be a 'backing' asset, and so Bitcoin is a 'backing' asset as well. So it doesn't even make any sense to say Bitcoin isn't backed by anything.
So of course Bitcoin has "real" value. Value is decided by the market. Bitcoin has had real value since 2010 when Bitcoin markets first opened to allow price discovery of its value.
A better question would be what gives Bitcoin its value. That would be its scarcity and utility.
Scarcity: only 21 million will ever exist. It has perfectly transparent scarcity (far improved over Gold) and an issuance schedule that can't be manipulated or changed (far improved over Gold).
Utility: originally its utility was as a way to pay anyone without intermediaries. Now there are thousands of other cryptos that can do the same thing essentially. So in the end the technology behind Bitcoin, while revolutionary, isn't the basis of its long term utility, because the code can easily be copied. The code was open source, so the code, and the design of the blockchain, was never the proprietary tech that gave Bitcoin its value.
So the real utility is in its network. Just like someone could copy Facebook's code but that copied website wouldn't be worth anything. This has been done thousands of times in crypto and nothing ever came close to having the utility of Bitcoin for being money. That's because the thing that sets Bitcoin apart is its network utility. It is by far the most secure, the most decentralized, the most trusted, the most accepted and adopted crypto network. That's its unique utility.
21 million scarcity + most incredible decentralized network in existence = massive value.
This is why every altcoin failed to become money and so now Bitcoin has no contenders as money from the crypto world. Because every single crypto besides Bitcoin failed to show anything close to Bitcoin's level of decentralization, security, trustworthiness, and inability to be controlled or manipulated.