No, my arguments do not fall down. You are making the terribly flawed assumption that bitcoin will always be this volatile. Bitcoin is less volatile than it used to be, and with greater adoption will continue to decrease in volatility.
The volatility in bitcoin today is nothing compared to 2011. Is it still bad ? Yes. Will it continue being bad ? Probably not. The long term trend supports the assumption that volatility will decrease with greater adoption.
Furthermore volatility has little effect on the 'money transmission' element of bitcoin as long as transfers and conversions take place immediately. It's still a viable way to legally move USD from the USA to Singapore with very low fees.
Another example, I'd like to add is that I had a large part of my savings in Indian Rupees. They depreciated by 30% over the past 2 years. That's definitely pretty bad but it didn't prevent me from buying coffee. Euros have also swung around by 15-20% over the past 2-3 years. The Brazilian Real lost 25% of it's value last year. Does that make them as bad as bitcoin ?
Your motivation for getting into bitcoin is your personal choice and I certainly hope that you profit from it. However, don't forget that bitcoin is an emerging technology going through fairly rapid adoption, as such, volatility, crashing exchanges, bubbles, bubble pops, etc. will be a part of it. And of course, I have to convert money from USD to BTC. Or from Marks to Euros. Or from escudos to Euros. That's just how it works.