I'm wondering why hasn't Monero taken off yet? Do you think government regulations have affected Monero's ability to go higher in price? If not, then what could be the reason? Is Monero a good long-term investment? Or are there better choices on the market (besides Bitcoin and Ethereum)? Your input will be greatly appreciated. Thank you.

It also depend on the demand of thr project in my opinion. If monero doesnt taken off yet that is because there are not enough hype or news that could bring it high. If a project has been talk of the town then surely it has a price movement being seen. I dont think the government can influence about its price. Its more like should be question about if institutions or whales are still gonna be interested with it.
Lets face it. Some geek or techwise who holds this coin arent deep pocketed enough, it still depends on whales. Without whales who can move it the price will move slowly.
I think that the reason here lies precisely in the possibility of tightening regulation of cryptocurrencies with a high level of capitalization by states and their governments. They do not hide it and some states have already banned Monero and some other coins with a high level of anonymity, such as ZCash and Dash. In the course of the struggle of states against money laundering and the fight against the financing of terrorism, it is primarily coins with a high level of anonymity that will be the objects of attacks, restrictions on circulation and even a complete ban.