I found where it is estimated that only 20% of Christians read the bible every day.
New Research: Less Than 20% of Churchgoers Read the Bible Daily
What I would focus on though is whether you are hearing God personally through the bible. The bible is not mere words, but through the Holy Spirit, it can give guidance and instruction in a very individualized way. Moving away from that instruction (personal revelation) is dangerous, you would be on a path that is only lit by what you have received in the past.
Consider the parable of the sower and the seed. Often so much of the word is lost to us because of stony hearts, or other hindrances. So to those people there would be little or no harvest and if they stop planting the word of God, then there is no chance of a future harvest. Even if you returned 100 fold on the word, at some point the harvest will stop if you quit planting. That person would be like a farmer who had a bumper crop one year, then doing nothing they expect a similar crop the next year? Sorry but that won't happen. Give us this day our daily bread. No daily bread = no growth. No planting = no harvest.
All that I have read in the word of God suggests that our prosperity at least in part depends on our meditating the word.
Joshua 1:8 (KJV)
8 This book of the law shall not depart out of thy mouth; but thou shalt meditate therein day and night, that thou mayest observe to do according to all that is written therein: for then thou shalt make thy way prosperous, and then thou shalt have good success.
Psalm 119:103-105 (KJV)
103 How sweet are thy words unto my taste!
yea, sweeter than honey to my mouth! 104 Through thy precepts I get understanding: therefore I hate every false way. 105 Thy word
is a lamp unto my feet, and a light unto my path.
Romans 10:17 (KJV)
17 So then faith
cometh by hearing, and hearing by the (rhema) word of God.
If the word is not too important as an ongoing endeavor, then why would god say to
Galatians 6:6 (KJV) 6 Let him that is taught in the word communicate unto him that teacheth in all good things.
Sure some can say many never had bibles, or could not read throughout history. That is why the law was read out out loud often in the OT and in the NT Paul tells Timothy:
1 Timothy 4:13 (KJV)
13 Till I come, give attendance to reading, to exhortation, to doctrine.
If anything, we all should consider reading more of the word of God and reading it with the right heart so that we can expect many harvests to come.