1. In 2017 the highest price reach $1200 and the lowest price $1000
2. In 2020 the highest price reach $5000 and the lowesr price $4500
But I doubt bitcoin can survive after 2025, because too many problem and replace with another cryptocurrency.
Slow transactions happen when you sent one with a very small fee or if the Blockchain is overloaded. This happened a few times and dozens of thousands of transactions were put on the "wait list". My transactions with very low fees compared to the recommended ones are usually confirmed in one day or even less.
at times like this the problem is not "low fees" at all but instead the competition that takes place.
if you look at the number of transactions currently waiting in the mempool they mostly have the minimal amount of fee but when something like this happens that minimal amount increases and keeps on increasing because of the competition which makes a normal fee of normal situation a low fee!
Indeed, even a transaction of 0.01 with 90k fee takes 20 hours for me now, if this keeps happening there will be no future for bitcoin. I can live with 1/2 hour confirmations but to become widely accepted the confirmations should become somehow instantly confirmed, also I think there will be a better future for a hybrid POS/POW coin then just a POW coin. Bitcoin will be replaced by something else someday in my opinion.