Just imaging that if you're buying Bitcoin 5 years ago , it's just 100$ for 100 Bitcoins. But it's now 12k$ per Bitcoin. You see the profit ?
To make it short, you'll earn huge profit when you hold your bitcoin for a long time.But of course saving it for a long time doesn't guarantee you to earn huge profit. Bitcoin price before is quite low, so if you bought bitcoin before, and hold it until now, you'll surely earn huge profit. But if you're planning to buy now and hold it for how many years, I don't think you'll earn huge amount since bitcoin price now is really high and it keeps on fluctuating. Maybe altcoin is way more profitable in holding it for long a time and not with bitcoin. Bitcoin for me is profitable when you hold it in a short period of time.
We dont know yet what the next move of bitcoin in the future mate, but I'm quite sure that it will be more valuable as the time passes. So I don't really agree with you that only for the short term technique could you make earn big profit from bitcoin because I beleive that holding for a long-term in bitcoin is the best way of investment among other coin especially into altcoin which you're preferring for.