It only took me a week and half to grind enough for full +20 legend POS set, pure Freetime-to-win player here.
Assume 1.5 week = 10 days, equally 240 hours, you don't do main quest after lv40 and play nonstop but rest 12 hours/day so you play 120 hours to get lv81 and a full set of POS legend +20.
From level 1~20: 5 hours.
From 20~40: 25 hours.
To get lv81 in F7 with pure boosters and boosts (including weekend boost), you'd need approximately 10 matches of VR, equivalently 7.5 hours and 1200 gold; 10 matches of FV, equivalently 8.3 hours and 1500 gold; 15 matches of HOP, equivalently 15 hours and 1700 gold; 10 matches of DV, equivalently 10 hours and 2000 gold. Totally from F7 you spend 40.8 hours and gain 6,400 gold. So you have 79.2 hours left and gain 7,500 gold during level 1~81 with pre 40 hero quests and pure F7.
To get POS ingredient, you need a set of black dragon and a weapon (approximately 14,000 gold for the set and 15,000 gold for weapon), 12 concentrated force (30,000 gold for cheapest), Star stone stuff (20,000 gold). Totally 79,000 gold.
For soulcraft, assume each equipment needs 20 purification stone (65 gold each) and 20 IS (currently 80 gold each), that would be 21,300 gold (fee included).
For enchant, assume each equipment needs 3 x 999 enchant dust (120 gold each), 20 IS and 15 RIS (100 gold each), that would be 7,000 gold (fee included).
So to get a +20 Legend POS set, you need 107,300 gold and have 79.2 hours to farm that among.
Thus you will need an income of approximate 1400 gold/hour! That's impeccably impossible for a newbie who has +5 weapon.