Why dont u recommend it? 
When the next bubble comes it would be nice to have a position leveraged 1:70
When the next bubble comes it would be nice to have a position leveraged 1:70 uhhh, have you ever seen the swings in BTC? if you are leverage 1:70, you better hope you get in at the exact right time. way too easy to get called like that.
Yeah the price would not raise up in a steady manner.. it can go up to 700 and then back to 680 and if you are in the wrong time you will lose 20 usd*70*your amount