"Still sane, Exile?"

After playing this game for several years, I'm not so sure.
Path of Exile is a free-to-play MMOARPG made by a team dedicated to the sensibilities of Diablo 2 and MTG.
In practice you've got to spend around $20 to have an easy time storing and selling things, which is ideal to do during a league season by buying a $30 supporter pack.
Path isn't for everyone, with unusual structure in how it must be played. "Outskilling" only goes so far, and the losses from death in the high levels (or Hardcore mode) mean that you can't just build a character willy-nilly. This is compounded by Path having one of the highest burdens of knowledge in an action game. There are thousands of very specifically worded things and niche interactions. You've got to play efficiently, be a little bit tanky, and usually focus on one or few skills for a given character. That last part can be very offputting to players coming from Diablo 3 or Torchlight, where hotbar diversity is somewhat greater.
Inevitably you will screw up your first character; then after you go searching for a guide on one that looks cool, you'll find it requires items you don't have or a character already near the level cap. Eventually you'll get the swing of things by finding semi-officially supported resources such as loot filters, trade macros, and third party item searches.
At that point your soul is sold to grinding gear in a Grinding Gear Games game.

Since I've finally hit 120/120 as of Incursion league, a perspective on the achievements:
You will not get every achievement in a single league. You might not get them in a single year. Path of Exile is an MMO and has an accordingly long grind to accomplish "everything". On the way you'll get distracted by interesting builds, league challenges which are themselves miniature achievements awarding permanent account-bound visual effects, and content like event races. As of the time of writing, I'm not even certain how certain achievements will be awarded going forward. A few of the exceptionally time consuming ones were rolled over into others as the content was removed or altered.
If you spent some months gaining power and then focused specifically on achievements, you could get a majority of them in a short window. Many of the grinds realistically only take 4-10 hours each, and the difficulty related achievements could be obtained in one playthrough.
To acquire all of them an aspirant must make several characters shaped to mutually exclusive builds, bring a Hardcore character to elderly levels, possess godlike patience, and hope lightning strikes twice.