Not true, making a blog, website, YouTube channel, Instagram or Twitter account all can gain you passive income from Google Adsense and affiliate products.
I have several domains with blogs on them that generate Adsense revenue daily and I have not added any content to them in a long time. Add content on a regular basis and it will only help with the traffic. Sure the initial investment and time and energy is needed, but this method is a very solid way for you to earn money passively once the initial setup is done.
Blog about what interests you, such as a hobby or what not. You don't have to be an expert and you certainly don't have to be incredibly knowledgeable to create content about a subject.
I follow one guy on Twitter that makes a YouTube video daily and all he does is read some highlights of articles from other websites revolving around cryptocurrency. These videos get several thousand views daily. Pretty simple.
Same thing with Instagram. All it takes is to post pictures, include tags in the post and gain followers. Include in your profile your website and in the post tell them to follow the link in your profile for more info, etc. That link then is your website with affiliate links, Adsense, etc.
If you're not currently utilizing what is available for FREE then you are missing out on opportunity. Sure we'd all like money for nothing, but at some point you have to put in some effort to reap the reward.