Oh my god... An asset with almost 30 billion dollars and you're asking whether or not it's useless. 
Yeah, and still more so given that Bitcoin is nowhere near being worth 30 billion dollars (or even 20B dollars)
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I thought increase in transaction fees is directly proportional to increase in Bitcoin value or prices
False, for the n time.. there is no link between the tx fee and the price of bitcoin.
Bitcoin could reach 100k but if there are no transactions or under 200k /day you could still send payments with 1 satoshi per kb.(and get confirmed)
Also, even if the price drops back to 1000 but we experience 10x more transactions get ready for fees up to 3$ for input
You are false and that got confirmed
Since you yourself mentioned transaction fees in dollar terms, it is as clear as day that the size of transaction fees is in linear dependence over Bitcoin price (provided all other things remain the same). I guess this is what the poster you replied to meant, i.e. transaction fees in fiat terms, just like you said yourself. After all, it was your claim that Bitcoin is there only because of fiat and people are ultimately interested only in fiat, not in Bitcoin. It kinda looks you should stick to your guns, shouldn't you?