How hard is it to learn Chinese?
"Mastering" Chinese can indeed take a long time to do, but getting to a very useful intermediate level is well within the reach of most people, and from that progressing further won't be that hard.
What makes Chinese easy to learn is the grammar. Chinese grammar is pretty straightforward for English speakers. Most sentence structures are similar to English and to make Chinese even easier to learn, Chinese has no verb conjugations, declinations ( as in Latin, German, or Russian), or hardly any inflections at all. More simply put - no irregular verbs, no verb tables, no noun plurals, no gender parts of speech or worrying about agreement. These complexities are present in Latin, German, and Spanish.
It's not that difficult if you're willing to commit to learning a new language. As an adult it's not as easy to pick up a language just by hearing it: you have to study and memorize vocabulary and grammatical structures, as well as use them. This takes time and effort. Unless you're an amazing learner, you can't learn a new language without time and effort. Chinese is just like any other language in this respect
Lets look at some of the most difficult aspects of learning Chinese. There are apparently over 80,000 Chinese characters. But, you only need to know 3,500 in Standard Chinese. This might seem like a lot, but you can actually get by with only !,000 of the most frequent characters and still read almost 90% of publications. That makes it a lot less difficult. And once you start learning the characters, like any vocabulary, you have to practice.
Modern Mandarin is a tonal language, meaning that words differ in meaning based on tone as well as pronunciation. Modern Mandarin Chinese has four tones (five if you count neutral tone) and depending on the tone used can change the meaning of a sound, such as from number eight ba to the term for dad ba. If the tone is high, ba means 8. If the tone is falling, ba means "dad". If the tone is falling and rising, ba means "to hold". If the tone is rising, ba means "to pull out".
In Chinese, tones are linked to each syllable's meaning, so that changing the tone can change the meaning. If you're a musical person, this probably be easier for you, but even if you are tone deaf, you can still get by. Chinese speakers might still understand you from context, it just might take longer to communicate.
I hope you find the idea of learning Chinese a little less worrisome.