Yep it's very easy to invest on cryptocurrencies, but the thing is it's not easy to choose and manage your investment.
If you think it's an easy peasy to invest, I'm quite sure losing will also be an easy peasy to you.
Small investments like $1 dollar a day, sounds like saving some penny everyday, since the OP wants to invest it on bitcoin, the total value of his investment will depend on the value of bitcoin, if it went down, he received negative roi, on the otherhand, he will receive positive roi and good profit.
Since the investment is for 5 years, the result of ROI still not guaranteed.