i m very glad that u have some questions like this... but in my opinion, u d better stop thinking like this....because it's too hard for u even for chinese... the current chinese comes from the old chinese. in the old chinese, each character has its meaning, whereas in the current chinese, we use more than one character, which can form a word and present one meaning. how do we pick the characters for a word? if u want to know about this, u must learn the old chinese. but this is too hard even for us. for example, in ur example, 润 in the old chinese means: the case that water go into the plant and the plant becomes well. now we use this character into 利润 to express that you invest in something and u get the profit and the profit makes you well. anyway, the old chinese is tooooooo hard. ur question is asking about the chinese culture, maybe u can focus on these questions when ur chinese is good enough~~

“润”也有“滋润”的意思。你有利益了，当然日子也“滋润”了！（lead a comfortable life）

這叫做 "同義複詞" 利=潤 潤=利 這裡 潤 ≠ 溼 潤 原意: 使得到好處 扶助 例如 : 澤加百姓 功潤諸侯《漢書》 --- 請相信我的答案

润有“滋养/帮助”的意思，比如“滋润了土地”不仅表示这块土地变湿了，也有“土地（上的植物）得到了（水分的）滋养/帮助”的意思。 所以“利润”的意思是这些钱/收入可以给（得到利润的人）带来帮助，也就是利益，因此用“润”这个字。